[all] Enhance code climate

[chrigl]

Is this a BUG REPORT or FEATURE REQUEST?:

/kind feature

What happened:

During #1853 I discovered that golint hasn't ran on the code base for quite a while now. We should improve code climate as indicated by make codeclimate.

This task might be solved in a series of PRs

What you expected to happen:

make codeclimate is "green"

make check will use the settings of make codeclimate rather than disabling plenty of checks

How to reproduce it:

Todo:

• [x] #1884
• [x] #1885
• [x] #1886
• [x] #1887
• [x] #1888
• [x] #1889
• [x] #1890
• [x] #1891
• [x] #1892

Environment:

• openstack-cloud-controller-manager(or other related binary) version: master
• OpenStack version:
• Others:

[chrigl]

/assign