Submodule: Update powerline, vim-popwindow, vim-virtualenv

switched default vim-virtualenv branch to 'integrated' to reflect my own
modifications to the plugin. Upstream integration will probably not
happen for a while.
Submodule: update vim-popwindow
vim: set bracket matching color in 'primal' color scheme
vimrc: NERDTreeFindToggle(), virtualenv, pylint, python3

Changes:
- NERDTreeToggleCWD() => NERDTreeFindToggle() with minor fixes
- updated virtualenv commands for python3
- pylint ignore list reset command: built it into program, never keybinded it.
- converted unittesting tools to python3