v0.5

Installed executable now gremlin instead of gremlin.py. Compensated
for LEAP API changes. (Note that gremlin still depends on the LEAP
develop branch and not on the official LEAP master branch releases to
take advantage of more up to date LEAP features.)

Added optional with_client async config section for code to be executed
after Dask client is started. This can be used to start worker plugins or
wait for a certain number of workers to become available.

setup.py now installs third party dependencies. Please note that the
latest LEAP version in LEAP develop will have to be installed.

Now better catch exceptions in LEAP code such that any errors that
propagate from there don't silently kill Gremlin.

Made a number of minor bug fixes and code format changes.