Remove buildConnector()

Instead of storing the application url in an attribut
and having to call buildConnector() each time one of the components
is updated, use a GetUrl() method which will build the url.

As this method is not called often,
this shouldn't have any impact on the performances.
Update libjson-rpc-cpp
Merge branch 'develop' into features/drop-buildConnector

Conflicts:
	src/mage.cpp
	src/mage.h
Make GetUrl() public
Update Makefile
Merge pull request #12 from MiLk/features/drop-buildConnector

Remove buildConnector()
Merge pull request #15 from MiLk/update-libjson-rpc-cpp

Update libjson-rpc-cpp
* Makefile bugfix
* Async calls (either deferred or truly async, configurable)
* Use clang for Android instead
* use c++_static as our STL instead of gnustl_static
* HTTP_CONNECTOR in CPP_FLAGS for Android
Define HTTP_CONNECTOR to include HttpClient header
* examples-clean, and run it on examples
* put the launch policy into a variable
Merge pull request #16 from stelcheck/features/async

Async
* Async callback (errors are not yet managed properly)
* Error handling for callbacks
Public github repo url in the README
Merge pull request #23 from MiLk/fixes/repo-url

Public github repo url in the README
Merge pull request #20 from stelcheck/features/async-callback

(WIP) Have the option to do async through callbacks instead of futures