Ignore import x.y.z as z cases for checker useless-import-alias

[sushobhit27]

Fixes / new features

• Better messaging for useless-import-alias and from imports #2309

[PCManticore]

I don't this needs to be ignored, just the message addressed to account for the from import. And maybe rename the message to something else.

[sushobhit27]

I don't this needs to be ignored, just the message addressed to account for the from import. And maybe rename the message to something else.

I was thinking that current checker should check only import a as a type cases and have a different checker for cases like import a.b.c as c, which can suggest to refactor it as "from a.b import c".

This way it will be more meaningful for each checker.

[coveralls]

Coverage remained the same at 90.057% when pulling f6c4407 on sushobhit27:fix_2309 into 7c103cd on PyCQA:master.

[PCManticore]

Okay, this makes sense. We can add a separate check.