Merge pull request #24 from francois-keith/master

Eigen minimum version is 3.2.0.
Export SumOfC1Squares symbol.
filter/derivative.hh: add missing include
[filter/vector-interpolation] Do not put data points in function title
[filter/vector-interpolation] Add time rescaling support.
[filter/derivative] Add support for TwiceDifferentiableFunction
[filter/derivative] Fix sparse matrix support
Allow allocation in n-times-derivable-function.hh for now.
Move vector-interpolation into roboptim-trajectory.
Install map.hh and map.hxx headers.
Enhance CONTRIBUTING.md
[filter/derivative] Fix jacobian computation and insert additional test
[travis] Clean and add initial debian support
[travis] Fix execution bits on scripts
[travis] Fix scripts
[travis] Import Travis modifications from debian branch
Remove bad assert
Update README.md
[travis] Use jrl-travis]
Synchronize