Changed the powerline location and added 'Tagbar'

This is due to the recent upgrade of the systent to ubuntu 14.04 LTS.
Added 'gvimdiff' function to zshrc
Added options for python dev.

Introduced flake8 from [https://github.com/nvie/vim-flake8]
Added simple date abbreviations for miscellenous

leaving code for a second, '_dt' will log time you left at the instant on the file being editted..
Cleanup the fugitive mappings
MatchTagAlways plugin: tag highlighting in markup