Refactors plugin to update his architecture and spoon version.

Plugin can now support spoon xml file to launch the plugin or
a configuration in pom.xml for some information (source folder,
output folder, processors, etc.). New architecture has been
imagined to handle spoon xml usage and no configuration file.
Adds usage in readme of the project
Fixes fragment parameter who didn't use config
Adds maven-compiler-plugin to compile in Java 1.7 by default
Merge pull request #1 from GerardPaligot/master