Allow the application to be deployed in a subdir

[daronco]

A few things need to be fixed to allow Mconf-Web to be deployed in a subdir in a server (e.g. "https://my-website.com/portal" instead of simply "https://my-website.com").

Hard-coded paths

There are places in the application where it assumes the application is deployed to the root of a webserver, thus preventing people from deploying it to a subdirectory.

They should be removed and replaced by relative paths so that the application works regardless of the path used to deploy it.

These are the paths that must be changed as reported in this thread:

./app/assets/javascripts/app/events/_invite.js.coffee:searchUsersUrl = '/mconf/users/select?limit=7'
./app/assets/javascripts/app/join_requests/invite.js.coffee:    url = '/mconf/users/select?limit=10'
./app/assets/javascripts/app/custom_bigbluebutton_rooms/_invitation_form.js.coffee:searchUsersUrl = '/mconf/users/select?limit=7'
./spec/models/user_spec.rb:      user.bigbluebutton_room.logout_url.should eql("/mconf/feedback/webconf/")
./spec/models/space_spec.rb:        space.bigbluebutton_room.logout_url.should eql("/mconf/feedback/webconf/")
./app/models/user.rb:      :logout_url => "/mconf/feedback/webconf/",
./app/models/space.rb:      :logout_url => "/mconf/feedback/webconf/"

Redirects

Was reported that "...when a registered user receives an invitation to join a conference, if he authenticates before entering the room, he is redirected to the home page instead of redirecting him to the room."

This possibly happens because Mconf-Web is considering the request as an external request. The redirect logic in ApplicationController should be reviewed.