first draft of cmake build scripts

available cmake variables:
  pfasst_BUILD_TESTS={ON,OFF}
    enable build of tests with automatically pulling in GoogleMock and
    GoogleTest (both version 1.7.0), building and linking it; no need
    for them to be preinstalled

what it also provides:
  - auto-detecting C++11 compiler flags for GCC and Clang

what it (yet) not provides:
  - handling of XL/C++ compiler
travis: first try of a Travis-CI config

most parts copied from cpp-netlib

cmake/travis: don't run test suite for gtest/gmock by default

heavily reduces build time (especially on travis)

travis/cmake: disable LLVM's libc++
Merge branch 'feature/travis' into feature/cmake
cmake: each test should output a XML for analysis
Merge pull request #3 from torbjoernk/feature/cmake

first draft of cmake build scripts
Break apart pfasst.hpp into pfasst-interfaces.hpp and pfasst-controller.hpp.

Also add pfasst-imex.hpp, pfasst-encapsulated.hpp, pfasst-sdc.hpp
and pfasst-pfasst.hpp.
Add basic test for pfasst::compute_quadrature.