Conditionally enable segment and clean up environment variables (#181)

* fix(deps): bumping frontend-platform to latest

This picks up a change in which a blank SEGMENT_KEY no longer causes the MFE to make a request to segment which results in a 404.

This was a requested fix for lilac.

* fix: cleanup environment variables

- Removes stray commas from the end of each environment variable in .env
- Removes CSRF_COOKIE_NAME completely - it is not used.
- Replaces default values with empty strings ‘’ - this will make the defaults falsy, rather than have them get converted to a string “null” value, which is very misleading.  It also enables the SEGMENT_KEY fix mentioned in the prior commit to work.

* fix: conditionally enable the segment middleware

Only add it if SEGMENT_KEY is truthy.

* build: bumping version number

.env

@@ -1,35 +1,33 @@
-NODE_ENV='production',
+NODE_ENV='production'
 NODE_PATH=./src
-BASE_URL=null,
-LMS_BASE_URL=null,
-LOGIN_URL=null,
-LOGOUT_URL=null,
-CSRF_TOKEN_API_PATH=null,
-REFRESH_ACCESS_TOKEN_ENDPOINT=null,
-DATA_API_BASE_URL=null,
-SEGMENT_KEY=null,
-FEATURE_FLAGS={},
-ACCESS_TOKEN_COOKIE_NAME=null,
-CSRF_COOKIE_NAME='csrftoken',
-NEW_RELIC_APP_ID=null,
-NEW_RELIC_LICENSE_KEY=null,
-SITE_NAME='',
-MARKETING_SITE_BASE_URL=null,
-SUPPORT_URL=null,
-CONTACT_URL=null,
-OPEN_SOURCE_URL=null,
-TERMS_OF_SERVICE_URL=null,
-PRIVACY_POLICY_URL=null,
-FACEBOOK_URL=null,
-TWITTER_URL=null,
-YOU_TUBE_URL=null,
-LINKED_IN_URL=null,
-REDDIT_URL=null,
-APPLE_APP_STORE_URL=null,
-GOOGLE_PLAY_URL=null,
-ENTERPRISE_MARKETING_URL=null,
-ENTERPRISE_MARKETING_UTM_SOURCE=null,
-ENTERPRISE_MARKETING_UTM_CAMPAIGN=null,
-ENTERPRISE_MARKETING_FOOTER_UTM_MEDIUM=null,
-
-BULK_MANAGEMENT_SPECIAL_ACCESS_COURSE_IDS=null,
+BASE_URL=''
+LMS_BASE_URL=''
+LOGIN_URL=''
+LOGOUT_URL=''
+CSRF_TOKEN_API_PATH=''
+REFRESH_ACCESS_TOKEN_ENDPOINT=''
+DATA_API_BASE_URL=''
+SEGMENT_KEY=''
+FEATURE_FLAGS={}
+ACCESS_TOKEN_COOKIE_NAME=''
+NEW_RELIC_APP_ID=''
+NEW_RELIC_LICENSE_KEY=''
+SITE_NAME=''
+MARKETING_SITE_BASE_URL=''
+SUPPORT_URL=''
+CONTACT_URL=''
+OPEN_SOURCE_URL=''
+TERMS_OF_SERVICE_URL=''
+PRIVACY_POLICY_URL=''
+FACEBOOK_URL=''
+TWITTER_URL=''
+YOU_TUBE_URL=''
+LINKED_IN_URL=''
+REDDIT_URL=''
+APPLE_APP_STORE_URL=''
+GOOGLE_PLAY_URL=''
+ENTERPRISE_MARKETING_URL=''
+ENTERPRISE_MARKETING_UTM_SOURCE=''
+ENTERPRISE_MARKETING_UTM_CAMPAIGN=''
+ENTERPRISE_MARKETING_FOOTER_UTM_MEDIUM=''
+BULK_MANAGEMENT_SPECIAL_ACCESS_COURSE_IDS=''