[PERF-303] Integer XBlocks/XModules into the static asset pipeline.
This PR, based on hackathon work from Christina/Andy, implements a way to discover all installed XBlocks and XModules and to enumerate their public assets, then pulling them in during the collectstatic phase and hashing them. In turn, the methods for generating URLs to resources will then returned the hashed name for assets, allowing them to be served from nginx/CDNs, and cached heavily.
XBlock Fragments expect unicode strings, and fail on an assertion when
it isn't:
```
2013-11-14 07:55:50,774 ERROR 3788 [django.request] base.py:215 - Internal Server Error: /courses/TestU/TST101/now/courseware/41d55c576a574fde99319420228f7f88/5fef5794e34842f4a2d45ebcdeaa9a3a/
Traceback (most recent call last):
File "/edx/app/edxapp/venvs/edxapp/local/lib/python2.7/site-packages/django/core/handlers/base.py", line 111, in get_response
response = callback(request, *callback_args, **callback_kwargs)
File "/edx/app/edxapp/venvs/edxapp/local/lib/python2.7/site-packages/django/contrib/auth/decorators.py", line 20, in _wrapped_view
return view_func(request, *args, **kwargs)
File "/edx/app/edxapp/venvs/edxapp/local/lib/python2.7/site-packages/django/utils/decorators.py", line 91, in _wrapped_view
response = view_func(request, *args, **kwargs)
File "/edx/app/edxapp/venvs/edxapp/local/lib/python2.7/site-packages/django/views/decorators/cache.py", line 75, in _cache_controlled
response = viewfunc(request, *args, **kw)
File "/edx/app/edxapp/edx-platform/lms/djangoapps/courseware/views.py", line 407, in index
context['fragment'] = section_module.render('student_view')
File "/edx/app/edxapp/venvs/edxapp/src/xblock/xblock/core.py", line 156, in render
return self.runtime.render(self, view, context)
File "/edx/app/edxapp/edx-platform/common/lib/xmodule/xmodule/x_module.py", line 903, in render
return block.xmodule_runtime.render(to_render, view_name, context)
File "/edx/app/edxapp/venvs/edxapp/src/xblock/xblock/runtime.py", line 356, in render
frag = view_fn(context)
File "/edx/app/edxapp/edx-platform/common/lib/xmodule/xmodule/seq_module.py", line 77, in student_view
rendered_child = child.render('student_view', context)
File "/edx/app/edxapp/venvs/edxapp/src/xblock/xblock/core.py", line 156, in render
return self.runtime.render(self, view, context)
File "/edx/app/edxapp/edx-platform/common/lib/xmodule/xmodule/x_module.py", line 903, in render
return block.xmodule_runtime.render(to_render, view_name, context)
File "/edx/app/edxapp/venvs/edxapp/src/xblock/xblock/runtime.py", line 356, in render
frag = view_fn(context)
File "/edx/app/edxapp/edx-platform/common/lib/xmodule/xmodule/vertical_module.py", line 27, in student_view
rendered_child = child.render('student_view', context)
File "/edx/app/edxapp/venvs/edxapp/src/xblock/xblock/core.py", line 156, in render
return self.runtime.render(self, view, context)
File "/edx/app/edxapp/edx-platform/common/lib/xmodule/xmodule/x_module.py", line 903, in render
return block.xmodule_runtime.render(to_render, view_name, context)
File "/edx/app/edxapp/venvs/edxapp/src/xblock/xblock/runtime.py", line 356, in render
frag = view_fn(context)
File "/edx/app/edxapp/edx-platform/common/lib/xmodule/xmodule/x_module.py", line 464, in student_view
return Fragment(self.get_html())
File "/edx/app/edxapp/venvs/edxapp/src/xblock/xblock/fragment.py", line 34, in __init__
self.add_content(content)
File "/edx/app/edxapp/venvs/edxapp/src/xblock/xblock/fragment.py", line 71, in add_content
assert isinstance(content, unicode)
AssertionError
```
