CI improvements

[halcyon]

Travis updates:

• Changed language from emacs-lisp to generic so that it passes validation in Travis WebLint
• Set sudo to false to explicitly send travis builds to Travis's new container-based infrastructure
• Use new version of evm updated to support container-based infrastructure
• PATH env variables needed for cask and evm are already set in travis-evm-cask.sh allowing us to simplify by not having to specify PATH as a global env and take advantage of defining multiple variables per item

Badge updates:

• Set branch for travis and coveralls
• Added melpa, melpa-stable and license

[ardumont]

Well, thanks!

Cheers,