travis: add cppcheck

Also, re-enable compilation using GCC.
Merge pull request #16 from toxeus/cppCheck

travis: add cppcheck
Initial commit for server built on ASIO.
Travis needs boost 1.53 at least.
Removed clang building until we can upgrade autotools to be aware of libc++
Merge pull request #20 from murrekatt/develop

Initial commit for server built on ASIO
Merge pull request #21 from monetas/develop

Merge develop into master