Added travis ci instructions

[bobhansen]

Added first stab at travis CI builds

Travis: added required packages

Travis: fixed package names

Travis: used ubuntu package names

Travis: added protobuf-compiler package

Travis: added boost date-time

Travis: dump boost dir

Travis: do apt-get install before compile for C++11?

Travis: explicitly add g++4.8

Travis: used update-alternatives rather than export CC

Travis: removed listing boost

Added BOOST_ASIO_DISABLE_STD_CHRONO for clang support

Travis: allow failure under clang

[bobhansen]

Fixes #46

[bobhansen]

Note that this doesn't currently pass; see https://travis-ci.org/bobhansen/libhdfspp/jobs/69768492

I'd like your comments on the failure; can you massage the master branch to get the CI build to compile and pass?

If we want it to run unit tests, we currently need to make it a java project and run things from maven. We should refactor the project to run it from cmake, perhaps running maven to run the tests if we need to.