Fix IPv6 gateway validation error message

Creating an IPv6 gateway exceeding 100 characters produces an error message stating that IPv4 gateway interface must not exceed 1000 characters.
Added 3G of RAM to instance view
allow setting a custom memory limit
use i18n trans
Merge pull request #423 from MaddinXx/custom-memory

Custom memory & responsive charts
Merge pull request #421 from aprt5pr/master

Fix IPv6 gateway validation error message
Add 768Mb
Merge branch 'master' of github.com:retspen/webvirtmgr

Conflicts:
	instance/views.py