Web front end for multiple marian MT systems

[santhoshtr]

• Uses Tornado for forking sub processes and communicate with them
• Define a configuration for language pairs and their models
• Build a simple web interface where language pair can be selected and content to translate can be submitted
• Define a web api at /api url which takes from, to, source params in the body content to POST. Returns json with translation as key for translated content.
• Remove all existing python scripts and replace it with server.py

[jorgtied]

• make this an optional interface / server instead of replacing the existing one
• keep existing files and setups instead of deleting them