Improved nml1 validation; now uses only schemas from local jar

Therefore jNeuroML should work too with without a local install of
org.neuroml1.model
Updating to v1.3.1 to match other v2beta3 repos
Update .travis.yml
Correcting version of injecting plugin
Merge pull request #3 from NeuroML/master

Update README.md
Adding license: LGPL
Merge pull request #4 from NeuroML/development

Merge to master for NeuroML v2beta3 release