Merge pull request #16 from openworm/development

Development
Merge pull request #17 from openworm/development

Updated model version
Merge pull request #18 from openworm/development

Release 0.0.4
Merge pull request #19 from openworm/development

Release 0.0.5-alpha
Merge pull request #20 from openworm/development

Geppetto 0.0.6 release
add tests
Merge pull request #21 from openworm/physicstests

physics laws tests
Geppetto release 0.0.7
Merge pull request #22 from openworm/development

Development
Adding .travis.yml for continuous integration
Don't run tests, find a way to install OpenCL drivers on the fly first
Attempting to install OpenCL-headers
using MODEL_TREE instead of generic statetree, also skeleton code in
place to populate WATCH_TREE when watching them variables
added TODO pseudo-code comments
populating watch tree when it's empty
added SPH watch visitor to update values one the tree has been built
cleanup some unnecessary code
Merge remote-tracking branch 'origin/development' into multiuser
implemented watch tree visitor
fixed broken tests