Commit quote changes left from previous branch
Split powerline.segments.common into a number of modules

Note: some modules (i.e wthr and bat) have their names in order to avoid the 
situation when module name matches segment name:

    import powerline.segments.common.weather

will import weather segment because `powerline.segments.common` contains line 
`from powerline.segments.common.weather import weather`.

Fixes #1083
Deprecate powerline.segments.common

Makes linter emit a warning
Add deprecation warning to powerline.segments.common
Merge pull request #1091 from ZyX-I/common-segments-split

Split powerline.segments.common module