v0.2.1

• rename method to Polytope.contains, was are_inside
• add method contains to Region
• deprecate function polytope.is_inside,
  use in and contains instead
• add arg solver to function lpsolve
• refactor by introducing new module solvers
• support MOSEK as solver, via function cvxopt.solvers.lp
• require numpy >= 1.10.0
• require matplotlib >= 2.0.0 for tests