Implement tags tab for VM and images (templates)

[bwsw]

Tags pane must be located when other tabs are located. It must support CRUD operations for tags, every tag is key-value, where key/value is 255 chars max length field. (Task for copying templates - #239

Tags must be lexically sorted and grouped by first part (the part is the tag name field string before first dot), e.g. "vm.".

VM
  vm.name1 = ...
  vm.name2 = ...

Credentials
  credentials.login = ...
  credentials.password = ...

If tag doesn't include "." then all those tags must be groupped into "Common" tab.

The frontend must support searching by substring with search field.

This task is prerequisite for #2