Makefile: VERSION uses "~" for "-" in git tags
Makefile: VERSION uses "~" for "-" in git tags

* This makes for better version comparison in distributions.
  In Debian, 3.0~rc1 < 3.0 < 3.0-rc1.
* Added version target to display computed version string
* Use the same variable for rpm and deb changelogs

roidayan/rtslib,Datera/rtslib,Datera/rtslib,roidayan/rtslib