Add maven-eclipse repository for SWT

[guillerodriguez]

Fixes #86.

[samskivert]

Hrm. I don't think this should be necessary. tripleplay/java-swt doesn't actually depend on anything from maven-eclipse.github.io, it just depends on playn-java-swt. playn-java-swt then depends on an artifact from maven-eclipse.github.io but it has a repository configuration for that Maven repo.

There's no way that Maven would require you to add repository declarations for repositories used by artifacts that you depend on, that would be crazy. So something else must have been causing this problem. I can't repro it, so I'm wondering where you encountered it.

[guillerodriguez]

What you say makes sense, but something must be wrong because I can reliably reproduce this. For that I just need to do the following:

1. Purge any locally installed copies of playn, tripleplay, and their dependencies
2. Checkout tripleplay master
3. mvn -U -B test >output.txt

The build fails with:

[ERROR] Failed to execute goal on project tripleplay-java-swt: Could not resolve dependencies for project com.threerings:tripleplay-java-swt:jar:2.1-SNAPSHOT: Could not find artifact org.eclipse.swt:org.eclipse.swt.cocoa.macosx.x86_64:jar:4.5.1 in jcenter (https://jcenter.bintray.com/) -> [Help 1]

The full output of the above command is attached: output.txt

Ideas?