OpenFst: 1.3.4 (updated)

OpenFst formula has been updated to the current version. Unlike the
previous formula, it now also passes two flags to `configure` which most
users will want (and which are needed for things which depend on
OpenFst). Once/if this pull request is accepted, I will make add two
other formulae for OpenGrm-Ngram and OpenGrm-Thrax, both useful tools
depending on OpenFst. NB: This is a squashed version of two previous
commmits.

Merge branch 'master' of https://github.com/mxcl/homebrew

"Keep url below homepage"
two style issues fixed

from @adamv:

    Style nit-pick: we prefer to keep --prefix... near the top of the
    options, so add these two new ones under that (and preferably each on a
    separate line.)

from @mistydemeo:

    You can use ENV.libstdcxx to force it to use libstdc++ with clang.
Remove trailing whitespace and commented-out code
changed download URL
restricted ENV.libstdcxx to mavericks and greater
openfst: add 1.3.4 bottle.