Added sources and javadoc artefacts.
Merge pull request #3 from BoD/maven-improvements

Added sources and javadoc artefacts.
Correction for Romme date calculation:

Between midnight and 1am on November 23 2014 was incorrectly calculated as 2 Frimaire 223 instead of 3 Frimaire 223
Added gradle files generated by "gradle init"
build.gradle: Speicfy utf-8 encoding for source files
gradle: specify the main class for the CLI jar.
Added HOWTO files for maven and gradle
gradle: added task to build a standalone jar for the CLI