Improving subversion support.

This ensures that .svn directories are ignored, and we use subversion's
list command to get files for performance.
Merge pull request #285 from Wilfred/master

Improving subversion support.
Add two other-window commands

These are projectile analogs for `display-buffer' and
`dired-other-window', with projectile bindings that mirror the bindings
in the `C-x 4' keymap.
Merge pull request #288 from kyleam/more-other-window-commands

Add two other-window commands
Invalidate project cache if .projectile is modified

This probably should have tests.