Added null check when processing content-type header

Updating the HUD with an AJAX request that has not content-type set causes the following error
 
Uncaught TypeError: Cannot call method 'indexOf' of null 

This is because type is not defined.

This was occurring when a server responded with a HTTP 204 and did not return a content-type header.
Merge pull request #401 from ScottGuymer/master

Issue #400 - Added null check to glimpse.hud.js > processContentType function
FIx #400 - Updated missed Glimpse.js update

Related to #401
Use default box-sizing for glimpse
Merge pull request #393 from schotime/boxsizing

Use default box-sizing for glimpse
Fix #413 - Make selector more specific
Fix #371 - Added override for spatial type in ProviderService
Fix #364 - Remove old code

Love the smell of removed code in the morning :tada:
Allowed direct loading of Ajax request from HUD
Fix #362 - Added defensive try/catch around System.Diagnostics.Process.MainModule call.
Issue #359 ASP.NET Ajax requests not displayed

ASP.NET Ajax requests have a content type of "text/plain" and so were
filtered out by Glimpse
Updated comment to match fix for Issue #359
Updated class level comment and fixed Unit Test
Tweaked comments
Merge remote-tracking branch 'upstream/master'
Update #371 - Update to support EF5 .NET45
Revert "Update #371 - Update to support EF5 .NET45"

This reverts commit 32d8777545bcab66a511e542517b459df0cf621f.
Update #371 - Update to support EF5 .NET45
Fix #426 - Update to get Inspectors
Work in progress for section resize