Enable doctests in Travis-CI
disable py.test colors for travis
Change imports for optimization module
Fix steffensen doctest
Workaround for pypy in the steffensen's doctest
Fix mpi_to_str doctest
Use ctx.zero in polyroots()
Fix tests in linalg.py
py3 fixes for doctests
SKIP sympy doctests
Fix doctests for matrices
SKIP rounding "doctests"
identify(): Use sorted(), while working with dictionary arguments (fix doctest)
Merge pull request #21 from skirpichev/travis-doctests

WIP: Enable doctests in Travis-CI