Add full URL support for the `--source_file` and `--schema_file` options

[salsferrazza]

The --source_file and --schema_file options currently imply file:// if using fully qualified URL syntax. Other protocols, such as http://, ftp:// and ws:// should be possible to resolve in this way, although ws:// would only be applicable as a protocol under --source_file and not --schema_file and would need to be implemented in a manner similar to the recent stdin support addition.

Example:

txcode --schema_file https://raw.githubusercontent.com/SunGard-Labs/fix2json/master/dict/FIX50SP2.CME.xml --source_file ftp://ftp.cmegroup.com/SBEFix/Production/TradingSessionList.dat --factory fix --source_file_format_type line_delimited