Added better support for pyenv, virtualenvwrapper, and autoenv
working in concert with one another.
Features added:
- Added a pyenv-virtualenv plugin which creates virtual environments
  using the current pyenv python version
- `cd` into a directory that has a virtual environment already created
  and autoenv will automatically activate that environment
- Current virtual environment is displayed in command prompt
Changed pvenv functions to avoid name conflicts
Run `pyenv virtualenvwrapper` and remove virtualenv-init cmd
Added pyenv-init to allow pyenv virtualenvwrapper to init properly
Skip workon if not in root directory
Added ability to enter a few characters at the prompt and then search backwards/forwards through history with up and down arrows
Moved arrow-keys-search-history from lib to available plugins
Merge pull request #365 from petedickson/arrow-keys-search-history

Arrow keys search history
inclued brunton theme
Delete brunton.theme.bash~
included safe battery charge to prevent error when battery plugin not enabled
deleted ~ file
Merge pull request #366 from benbrunton/master

Added new theme
prevent battery_charge call from erroring in themes when battery plugin not enabled
Merge branch 'master' of https://github.com/revans/bash-it
updated brunton theme to use battery_charge
Merge pull request #367 from benbrunton/master

Ensure that battery_charge function is safe to use in themes
create postgres helper functions for bash_it
Merge pull request #370 from eddietejeda/postgres_plugin

Fixes #369. Create postgres helper functions for bash_it
grep v2.21 compatibility

grep v2.21 depracates GREP_OPTIONS env var