Added support for plugin dependencies using Sponge API
Missing plugin dependencies are now shown
Merge branch 'sponge-dependencies' of https://github.com/alexander0153/Granite into alexander0153-sponge-dependencies

Conflicts:

src/main/java/org/granitepowered/granite/impl/plugin/GranitePluginManage
r.java
Merge branch 'alexander0153-sponge-dependencies' into sponge