Mef_eline should log the creation and modification of an EVC

[italovalcy]

Hi,

When we request an EVC from mef_eline, the only thing that is logged by default is (Kytos was started using docker image kytos/nightly and using the command kytosd -E):

Sep  9 19:56:20 313bfc683bdd kytos.napps.kytos/mef_eline:INFO models:245:  EVC bfaaaefbf1604d5b8f535912d024190b was synced to the storehouse.
Sep  9 19:56:20 313bfc683bdd kytos.napps.kytos/mef_eline:INFO storehouse:104:  Box 741dddebabc34ca980396cb91a05f0c8 was updated.
Sep  9 19:56:21 313bfc683bdd kytos.napps.kytos/mef_eline:INFO models:245:  EVC bfaaaefbf1604d5b8f535912d024190b was synced to the storehouse.
Sep  9 19:56:21 313bfc683bdd kytos.napps.kytos/mef_eline:INFO models:596:  EVC(bfaaaefbf1604d5b8f535912d024190b, Vlan_211_ClientA) was deployed.
Sep  9 19:56:21 313bfc683bdd kytos.napps.kytos/mef_eline:INFO storehouse:104:  Box 741dddebabc34ca980396cb91a05f0c8 was updated.
Sep  9 19:56:21 313bfc683bdd kytos.napps.kytos/mef_eline:INFO storehouse:104:  Box 741dddebabc34ca980396cb91a05f0c8 was updated.

It looks like if you want to have more information about EVCs being created, you should enable DEBUG logging (https://github.com/kytos/mef_eline/blob/master/main.py#L164). However, debug logging also comes with lots of unnecessary information that does not fit in the production environment.

My suggestion is that: creation, modification, or disabling an EVC should generate logs as informational. When the evc deployment fails for any reason, this should be logged as an error. When the path change because of any event, it should be logged as informational.