Fixed comment typo

Minor typo.
Merge pull request #786 from tewha/patch-9

Fixed comment typo
Ensure content type for path extension doesn't return null
Merge pull request #792 from zachwaugh/master

Fix content type for extension from returning null
[Issue #791] Matching operations on request URL path rather than absolute URL string
Merge branch 'master' of github.com:AFNetworking/AFNetworking
Adding comma (,) as a percent escaped character since it's in the reserved words per the RFC
Fixes -[AFURLConnectionOperation totalBytesRead] threading issue.
Merge pull request #825 from OliverLetterer/thread-issue

Fixes -[AFURLConnectionOperation totalBytesRead] threading issue.
Adding missing #pragma clang diagnostic pop (/thanks @tewha)
[Issue #817] Removing unused totalContentLength and offsetContentLength properties, and implementation of -connection:didReceiveResponse:
Merge pull request #814 from madninja/bug/percent-escapes

Adding comma (,) as a percent escaped character
[Issue #803] Only set image in UIImageView category if non-nil

Signed-off-by: Mattt Thompson <m@mattt.me>
Merge branch 'master' of github.com:AFNetworking/AFNetworking
[Issue #837] Refactoring implementation of HTTP string encoding edge case to -responseStringEncoding to fix potential inconsistency in effective value
Rework delivery of AFNetworkingOperationDidStartNotification and AFNetworkingOperationDidFinishNotification to avoid crashes when logging in response to notifications
Set indentation settings to four spaces at the project level
Update network activity indicator only if requests have a non nil URL
Merge pull request #843 from blakewatters/bugfix/avoid-logging-crashes-from-notifications

Rework Notification Delivery to Avoid Crashes in Logging
Merge pull request #842 from 0xced/no-nil-network-activity

Update network activity indicator only if requests have a non nil URL