Update 0.7.3

[superolmo]

• Added Initial PyTest and Coverage
• Added timestamp field "added" to Series to match channels "added" field
• Added string field "url" to Series to quickly get the series download address
• Added new API "get_last_7days()" returns the last added streams in the last 7 days in JSON format
• Added new API "get_download_progress()" returns information on the current download stream in JSON format
• Changed internal function _load_series_info_by_id_from_provider to allow returned value to change to JSON
• Changed search_stream function to only search in specific collections
• Refactored "rest_api.py" to make it easier to extend in the future
• Added new rest API
• Changed to Poetry environment
• Changed Functional Test to test loading series information
• Changed sample index.html to test more features
• Fixes search_stream fails with TypeError when stream.name is None #15