Disable signify for now
Miscellaneous changes to different plugin configs

- Disable netrw altogether, since I'm using vimfiler anyway.
- Add an "Unite grep" invocation in Unite's main mapping.
- Enable airline's tabline extension.
- Set g:clang_make_default_keymappings to 0 (only in my branch for now).
Add commented out code for editing binary files

Is code minimally modified from the docs. Should be converted to a plugin or
find one equivalent.
Update plugins. Move clang_complete to my fork