Pomo release 0.7.2

Cross-platform binaries are no longer supported because they're annoying
to maintain.

A source build of pomo is available for Arch users at https://aur.archlinux.org/packages/pomo-git/

OSX users should either build from source also see
https://github.com/kevinschoon/pomo/issues/1 (pending)

* Updates termui to v3 and various other dependencies
* Removes code for generating cross-platform binaries
* Delete socket file after accidental crash (@strogiyotec)