Htchirp

- [HTCONDOR-1394](https://opensciencegrid.atlassian.net/browse/HTCONDOR-1394) The phasestring method is no longer suppported.
- [HTCONDOR-2012](https://opensciencegrid.atlassian.net/browse/HTCONDOR-2012) The client now looks at `$_CONDOR_CHIRP_CONFIG` for the location of the config file.
- [HTCONDOR-2142](https://opensciencegrid.atlassian.net/browse/HTCONDOR-2142) The condor_starter proxy now supports up to 5120 bytes per command and the client now catches too-long commands before sending them to the proxy.

- Adds `condor_chirp`-like command line interfaces to `htchirp.py` and the HTChirp package

- Added context manager to `HTChirp` class

Initial release