Do not detect language if it is a binary file.
Updated language list to include HOW, and fixed the lack of lexer problem.

Because HOW does not yet have a standardized lexer, I left the "lexer" field as "Text only".
Adding support for Hoplon files

See https://github.com/tailrecursion/hoplon-demos/blob/master/todoFRP/src/index.cljs.hl for an example and https://github.com/tailrecursion/hoplon for the full project.
Minor README
add Cirru with some samples
add interpreter for groovy language
Merge pull request #907 from github/groovy-interpreters

Add interpreter for Groovy language
Merge pull request #906 from Cirru/master

add Cirru with some samples
Travis settings
add interpreter for coffescript
Add .es6 as JavaScript extension.
adding ATS and several sample files
Merge remote-tracking branch 'upstream/master'
fixed extension order in languages.yml
Merge pull request #910 from abuiles/es6

Add .es6 as JavaScript extension.
adding more varied examples, including an .atxt file
Merge pull request #909 from github/coffescript-interpreters

Add interpreter for CoffeeScript
Add heuristics for '.cl'.
Merge pull request #913 from larsbrinkhoff/cl

Add heuristics for .cl
Support of the .ecl file extension for Prolog.