implement core metadata CRUD workflow, update CLI architecture

[tomkralidis]

• separate DB debugging to separate stream
• update CLI subcommand architecture
• separate PostgreSQL specific pip requirements
• implement core metadata generic CRUD functionality
• add CRUD workflow for contributors
• add CRUD workflow for stations
• move data ingest --verify-only into dedicated subcommand (data verify)
• remove Python 2 support
• add logging
• normalize wmo_region_id across models
• add __geo_interface__ property to core models
• update ES index creation settings
• add project class/model
• add number_of_observations to Extended CSV object

[coveralls]

Coverage decreased (-5.2%) to 59.873% when pulling 8cf9dea on tomkralidis:updates into 6c8976f on woudc:master.