fixed project build

The project could not be built in the console (on Ubuntu 14.04) due to:
* version incompatibility (Java version 1.3 was assumed)
* non existing artifact virtjena2 v1.0.0

For this purpose, following modifications were done
* moved aksw repository definition to parent, change virtjena artifact to virt_jena2:7.1.0
* set source version to 1.7 in parent pom
* added .gitignore files (to avoid commiting eclipse configurations & target folders)