Enable Bundler caching on Travis
Merge pull request #183 from duggiefresh/master

HTTPS in Gemfile, SSL verification with Rubygems
Merge pull request #184 from duggiefresh/cache-bundler

Enable Bundler caching on Travis
NMatrix::has_clapack? method to determine whether CLAPACK has been
linked. Also, an exact inverse method for rational numbers and for
systems without CLAPACK.
Merge branch 'master' of github.com:SciRuby/nmatrix
Fixed stupid mistake involving what the new exceptions inherit from.