Remove deprecated code, arguments, open source public repo created!

Breaking changes:

• db_name is required on the command-line for table sources and targets.
• JobContext renamed to Session, factory functions moved to Session initializer.
• Remove logging, temporary file management and argument parsing/JSON validation responsibilities of JobContext/Session.
• Remove deprecated schema_sql argument in sources
• Remove deprecated lpass_show()
• Remove deprecated schema/table/engine params to dataframe() source

New features:

• Repo made public! LICENSE.md, CODE_OF_CONDUCT.md added.

Bug fixes / reliability improvements:

• Allow use of library without pandas installed
• Allow user to specify psycopg2 variant when installing as a library.
• Address dependency conflicts with PyYAML
• Gracefully recover if Redshift admin schema SQL view not installed

Other updates:

• Document use and installation steps in README.md and INSTALL.md