update ycm and snippet plugins

Adds vim-snippets since ultisnips no longer bundles in snippets.
update example vimrc.mine
rm old snippet submodules
rm solarized
rm dupe tern plugin
update all but minibuf

Massive plugin update. Don't update minibuf since that includes a
breaking change to keyboard shortcuts.

This was basically `git submodule foreach "(git checkout master; git pull)&"`
though there were some manual changes to minibuf (since we didn't want
to update that) and powerline (since that origin uses a dev branch).
update minibufexpl

Includes change to vimrc because minibuf dropped support for many
shortcuts.
powerline -> vim-airline

vim-airline is actively maintained. vim-powerline hasn't been touched in
a while, and the new Python version is still in beta.
rm arm syntax highlighting submodule