Add common "select all" command to keymap.

I noticed this mode was missing this shortcut I use quite a bit in Emacs, and for some reason "pmeta-a" was disabled for highlighting all of the text in a "buffer".
0.0.4

Signed-off-by: Chris Granger <ibdknox@gmail.com>
C-x C-e eval-editor-form (like eval-last-sexp)
Merge pull request #15 from christianromney/master

C-x C-e eval-editor-form (like eval-last-sexp)
Merge branch 'patch-1' of https://github.com/lambdahands/Emacs into lambdahands-patch-1
Merge branch 'master' of github.com:LightTable/Emacs into lambdahands-patch-1

Conflicts:
	emacs.keymap