Rewrote HttpTransmition to use Java URL.

Refined project build.

Added developers clause.
Bumped sbt version, bumped library dependencies version.

Removed commons from the dependencies.

Core, http and transport implementations (http-java and http-android)
are now considered modules and are not individualy
published. They are instead added to the sources of project dsl-clien-http-android
and dsl-client-http-java. Which are the names under which they are published.