Merge pull request #15 from randy-waterhouse/develop

configure.ac added many more standard checks.
Gitignore updates
Merge pull request #17 from yamamushi/develop

Gitignore updates
travis: remove clang compilation

Since the environment variable CXX was overridden in the script section
of the .travis.yml file the compilation was effectively never done
using clang. Trying to conditionally override CXX for GCC only will
result in compilation errors using clang probably due to missing
compilation flags. This will be fixed in a upcoming commit.
travis: add cppcheck