UI is no longer working with mef_eline

[italovalcy]

Due to some updates on the mef_eline API (which should have increased the version of the API, but it didnt), the UI is no longer working to create EVCs.

Steps to reproduce:

1. Install Kytos and mef_eline (+dependencies)
2. Start Kytos with: kytosd -E
3. Create a topology on mininet, such as: mn --topo liner,3 --controller=remote
4. Go to the Kytos UI and click to create a new EVC, with the following parameters:

• UNI A: 00:00:00:00:00:00:00:01:1
• UNI B: 00:00:00:00:00:00:00:03:1
• tag type: 1
• tag value: 100

Expected: the circuit should be created

Actual behavior: Bad request (only seen if you enable developer mode)

Point of attention:

1. Fix the parameters (tag_type / value changed the names) and include the missing ones (dynamic_backup_path - see Name and default value of "dynamic_backup_path" mef_eline#198)
2. If the request is returning an error, the UI should raise an alert to say that some went wrong

[Niehaus]

@italovalcy I started to work on your problem, so I implemented #71 that can be used to raise an alert when the request return an error