Add Github's Objective-C .gitignore file.

This prevents .DS_Store and xcuserdata files/dirs from causing
the AFNetworking submodule to always have `(untracked content)`
listed in `git status`.
Update Example/Classes/Models/Post.m

Adapt to app.net global stream response change
Update Example/Classes/Models/Post.m

Sorry the previous commit left 1 crucial line :(
Merge pull request #594 from ijohn/patch-1

Update Example/Classes/Models/Post.m
Set the dot (.) to be unescaped (fixes #597)
Merge pull request #598 from dtorres/patch-1

Set the dot (.) to be unescaped (fixes #597)
Fix typo in AFXMLRequestOperation block.
Merge pull request #602 from modocache/fix-xml-typo

Fix typo in AFXMLRequestOperation block.
use the weakself/strongself pattern to fix AFHTTPClient not being released

see AFNetworking issue #581
Merge pull request #612 from Madefire/afhttpclient_no_dealloc

fix for AFHTTPClient not being released
Minor reformatting of weak/strong self pattern for network reachability callbacks
Break retain cycle for background tasks
Using __weak reference in setCompletionBlock:
Using conventional weak/strong self pattern to break retain cycle in background tasks
Merge pull request #588 from natestedman/master

Add Github's Obj-C .gitignore
Updates AFJSONRequestOperation to allow JSON parsing options since it is now using the NSJSONSerialization class by default
Renaming parseOptions property to JSONReadingOptions

Updating documentation for JSONReadingOptions property
Merge branch 'master' of github.com:AFNetworking/AFNetworking
Removing excess whitespace
[Issue #592][Issue #600] Changes the logic of UIImageView -setImageWithURLRequest:placeholderImage:success:failure: such that if the success block is specified, the default behavior of self.image = image is not executed. This allows for full customization over any post-processing on the image, or the animation to be used when setting the image.