Test case for connected routes

[bewing]

I don't know how #157 got so horribly screwed, so I just deleted everything and started over.

Depends on:

• eos - Add new test for connected routes napalm-eos#101
• junos
• iosxr

[mirceaulinic]

Putting this on hold till we'll have the implementation available on all drivers.

[dbarrosop]

Updated the description of the PR adding a list of devices we have to implement this for. We can create issues if we prefer and link them here if we prefer.

[manuel-domke]

Hi,
I just added a IPv6 implementation to get_route_to in the iosxr driver.

Now I need to extend this testcase to IPv6 destinations for my changes to pass the CI.
Any comments on that?

[dbarrosop]

This other PR, which is similar to this one, made me think:

#233

Quoting myself from that other PR: "I was wondering if we should just remove the "protocol" from test_get_route_to so we can control with the test cases (default and the rest) the data we get and parse instead."

[dbarrosop]

Please, see: #238