New formula: OpenGRM-NGram

OpenGRM-NGram adds language-modeling and smoothing support to OpenFST
(upon which it depends).
Ruby style guide adherence

The formula has been run through `rubocop`, which checks for adherence
to the Ruby Style Guide. There are just two warnings remaining: the URL
line is too long (which I'm ignoring) and that I should have top-level
documentation (but other Homebrew formulae don't, normally).
Added tests based on OpenGRM-NGram homepage
Non-trivial tests
opengrm-ngram: add 1.1.0 bottle.