Thredds-crawler

- fixes a bug when crawling FMRC datasets

- Added ability to [authenticate](https://github.com/ioos/thredds_crawlerauthentication) against thredds catalogs
- Logging improvements
- CI / testing improvements

With release of 1.5.1 we have changed the open source license from the strict GPLv3 to the more permissive MIT license. We have also transferred the project from asascience-open to the ioos organization to increase visibility and promote open source collaboration.

- Don't verify SSL

- Added multi-threaded support. thanks lukecampbell
- Better date parsing. thanks akorosov
- Travis cleanup
- Py 3.5 compat