Fixed HttpRequest to remove the overwritten header in AsyncHttpClient  constructor
adding Looper to AsyncHttpHandler constructor to allow constructing them on background threads
Merge pull request #653 from aaboyd/master

Allow users to pass in Looper to be used instead of forcing synchronous mode
Merge pull request #650 from JedYu/master

remove the overwritten header in AsyncHttpClient  constructor
Split timeout into connection and response timeouts, for optimal control.
Javadoc correction.
escape json string value
Merge pull request #657 from fineswap/timeoutC

Split timeout into connection and response timeouts, for optimal control.
Merge pull request #660 from wada811/master

Escape json string value
Escape String values.
Merge pull request #663 from fineswap/JsonStreamerFix

Escape String values.
Add pre-processing for requests and responses.
Added missing interface file.
Make pre-processing work per request and accompanying response.
Remove wrong file.
Add pre- and post-processing for request and response.
Remove old file.
Sample for pre- and post-processing requests and responses.
Add a note about which thread calls pre- and post-processing methods.
Introduce an interface for adding arbitrary JSON objects.