Use indexes for array parameters
Store array/list size in a local variable for performance
Cast params to string by default
Enable changing handler's operation mode in run-time.

The handler had a bug when switching from async to sync, and vice-versa.

Because the handler variable was final, switching from async to sync would not free the retained memory. Also, and more importantly, if the handler was sync and then switched to async, a NPE would result because the handler was always null from before.

This is now fixed.
Add getThreadPool() method to return current thread pool used.
Small logical error.
Enable custom classes to override the default threading behavior.
fix an exception
Merge pull request #526 from ldiqual/master

Use indexes for array parameters
Merge pull request #528 from ldiqual/bugfix/default-cast-string

Cast params to string by default
Merge pull request #533 from superdry/fix

fix an exception
Merge pull request #531 from orientalsensation/AsyncHttpClient

Added ability to get thread pool or set the default one when extending.
Merge pull request #530 from orientalsensation/AsyncHttpResponseHandler

Enable changing handler's operation mode in run-time.