Merges branch 'release/0.1.31' into develop
Adds RIML_DIR to use @tek's fork.

* RIML_DIR => path to git clone of @tek's fork.
* If present, the RIML_DIR/lib/riml and RIML_DIR/bin/riml will be used
  respectively.
* If absent, defaults to rubygems riml
Bumps version to 0.2.0
Updates changelog.
Merges branch 'release/0.2.0'