Preparation for renaming repository blpapi-node.
Update to v0.1.8.
Merge pull request #20 from apaprocki/rename

Preparation for renaming repository `blpapi-node`.
Added support for request overrides.

Javascript Object values were previously not allowed as values in
the request object.  Now, if the specified key is "overrides", an
Object value will be marshaled into the `blpapi::Request`.  This
allows for "overrides" to be specified in a request as documented.
Merge pull request #22 from apaprocki/request-overrides

Added support for request overrides.