Updated all plugins that are non-forked. Added some new plugins.

Added update_plugins.py which can fetch new plugins from GitHub.

New plugins added: zencoding, vim-indent-object, taglist, nginx.vim
Updated documentation
Reverted back powerline
Reverted powerline version. Increased font size
Fixed some things in peaksea (regarding omni menu and folding in terminal mode). Optimized a bit colors for powerline
Ignore docs tags
Removed generated doc tags from git repo
add support to clipboard
Merge branch 'master' of ssh://github.com/billhsu/vimrc