Bug 7764: rework the INSTALL.ubuntu instructions

This is a major rework. Key improvements include:
- Removed confusing multiple versions for Ubuntu leaving only one set
  of instructions.
- The packages koha-deps and koha-perldeps are used.
- License has been updated to reflect GPL3.
- More wiki reference links have been included.
- It is aimed to be based on source, not just tarball or just git.
- Sample output has been cut as much as possible.
- Almost cut-and-paste easy, making it friendlier than INSTALL.debian.

Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Fixed a tiny typo: seperate
Makes all sense to me - only wondering a bit about the recommendation
of using lynx for the web installer.
Quite an improvement, so passing QA.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Bug 7764: (follow-up) editorial tweaks

Besides some grammar and capitalization corrections, this patch
adds a link to the wiki page for installation Koha on Ubuntu
from packages.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>