Fix for #550, including unit tests.

Now makes list, before returning it, if it doesn't exist. Previously
returned new, empty IEnumerable, each time.
Test was making assumptions about *type* of IEnumerable being returned.
Adding form variables to the request tab
Checking for null form variables
Update #553 - Fix up some logic errors in proxy code
Merge pull request #564 from kellystuard/fix-550-trace-logging

Fix for #550, including unit tests.
Fix #590 - Implemented fix which saw the browserlink URI blacklisted
Fix #591 - Update to HUD filter code
Minor update to release notes
Use reflection to determine form variables
Add test trace output to webforms page
Update typo in the release notes
Update ViewState inspector to capture page ViewState
Remove finial RC safe gaurds
Additional RC safe gaurds removed
Fixing naming
Added Http Header fields to RequestModel and RequestModelConverter
Cookies accessed by reflection now.
Querystring accessed by reflection now
Fix #594 - Update page adapter proxy check logic
Update webforms packages prior to release