Variables as functions

Merge pull request #123 from JuliaDiffEq/parameter

simplified interface for declaring parameters

Massive overhaul

v0.1.0

Update .travis.yml

Fix for units handling

Merge pull request #72 from JuliaDiffEq/myb/unit

Ensure that the returned values have correct units

Initial Release

v0.0.1

pass version to generated ODE function