Improve automated loading of data files and (re)starting otp server

[miraculixx]

The current setup requires the manual reconfiguration of nginx, because the (re)started docker container will have a new IP address everytime => currently requires manual effort for initial load and restart. This needs to be fully automated.

Expected behavior

1. Building the graph and starting nginx is one single command.
2. Rebuilding the graph can be done from the client command line (rather than entering the full docker command on the server)
3. Nginx is automatically (re)configured/reloaded so it catches the new IP address of the restarted docker container

Command lines

# server, specify as many --urls as you want, add multiple options in quotes 
server$ /path/to/script/loaddata --url <url> --options <options>
# client
client$ fab loaddata:server=<fabric role>,urls=<url1 for gtfs file[,url2[, ...]]>,options=<options>

Implementation notes

• the fabric command shall be implemented as simple wrapper to call some server-side script(s), so actually the fabfile.py will (almost) be as simple as e.g.

@task
def loaddata(server,urls,options):
    # figure out the host to run on
    # see http://stackoverflow.com/a/6313237/890242
    # need to pass on options
    run('/path/to/serverside/script/loaddata`)

• The rationale for the above is such that we can easily implement server side processes using the very same commands, e.g. scheduled reloading once a day etc.