Added single quote to the chars to escape

Ran into some issues with sending an unescaped apostrophe,
but by adding it to the list of characters to escape, this problem
is now fixed for me.
Merge pull request #713 from ericflo/patch-1

Added single quote to the chars to escape
Adding credential property to AFURLConnectionOperation
Adding AFHTTPClient -setDefaultCredential:
Merge branch 'master' of github.com:AFNetworking/AFNetworking
Fix request stream exhaustion error by copying the original NSInputStream
[Issue #715] Fixing warnings generated by earlier versions of Xcode (/cc Ignacio Rodrigo)

Minor reformatting
Merge branch 'stream_exhausted_fix' of https://github.com/aburgel/AFNetworking into aburgel-stream_exhausted_fix
Minor reformatting
Re-ordering NSURLConnectionDelegate method implementations
Marking connection parameter in connection:needNewBodyStream: as __unused
[Issue #719] Adding shouldUseCredentialStorage property to AFURLConnectionOperation /thanks Xihe Yu
Updating list of implemented NSURLConnectionDelegate method
Adding AFNetworking architecture diagram
Fixing link to diagram in README
Fixing center alignment
Update README.md