Update bitly_api/bitly_api.py

Fix duplicate function name "bundle_collaborator_remove".
Update user_link_history

* Use "on", "off", "both" instead of invalid booleans
* Add private option, which also uses "on", "off", "both" options
Add v3/link/encoders access
flake8 shows no issues.
Add Apache 2 license.
Add .travis.yml and testrunner script.
Handle non-string parameters.
Add unit_reference_ts to _call_oauth2_metrics
Version 0.3
change package name
change package name
rename bitly_api to bitly_api3
Remove "long"