fixed packaging API in jar
Include getAPIVersion and getImplementationVersion

This includes the getAPIVersion and getImplementationVersion methods added
to SpongeAPI (SpongePowered/SpongeAPI#12).

The only quirk right now is that they both return the same value.

Signed-off-by: Steven Downer <grinch@outlook.com>
Merge pull request #13 from Grinch/master

Include getAPIVersion and getImplementationVersion
Add build task to default tasks

Updated the README to account for this.

Signed-off-by: Steven Downer <grinch@outlook.com>
Merge pull request #14 from Grinch/patch-1

Add build task to default tasks
Update pre-commit hook to only do license formatting
Update README PR guidelines

Based on feedback so far
Add Contribution Guidlines link to README
Merge pull request #16 from simon816/readme-guideline-link

Add Contribution Guidlines link to README