[CTest+valgrind] Add suppression file for HDF5 leaks
[CMake] raise cmake requirement to 2.8.10

In order to parse gcov output from gcc >= 4.7 we need a cmake
that is more recent then 2.8.9 [1]. Raising it to 2.8.10 is in sync
with the debian branch, so lets pick that.
CMake was backported to precise in the pandora ppa to not break
travis.

[1] http://public.kitware.com/Bug/view.php?id=13121
[CMake] Add coverage support (if compiler is gcc)
[CTest] Add support for coverage (unix/travis)

We hardcode gcov-4.8 for travis' ctest script for now.
[CTest+travis] Set DEBUG build only ctest not in travis.yml
[travis] Adjust ctest verbosity based on the compiler

For gcc based build we now have coverage support. That
generates a lot of debug output, which might overflow travis'
4MB limit. More silence is in order.
[CTest] Set --output-on-failure for ctest