Improve accuracy of javascript-escape linter: Previously this would
match on FOOescape() and FOO.escape calls, but neither are the global
escape function we are worried about.
The regex probably isn't 100% accurate; there may be still false
positives (javascript allows a large range of characters in identifiers,
some of which may not be covered by [\w.$]). The main thing is to avoid
false negatives here though - this will definitely catch any use of
`escape()` or `window.escape()`.
Also remove javascript-interpolate lint - this was deemed unecessary.
StringUtils.interpolate is not in fact safe (it does no html escaping),
so the results of this lint are misleading.
This was failing before because DDT was trying to get an attribute
from an XSS Lint RuleSet object but that was throwing an exception
because the RuleSet object didn't have that attribute.
In python 2 such exceptions were automatically swallowed by the
getattr function but in python 3 they get raised.
