Applied fixes provided by Offiria & some of my own

Fix Applied: Specify max-width value for mobile view login #68
+ Fix Applied: Fix PHP 5.4 strict standard error in mobile view #67
+ Fix Applied: User invited only to specific group should not be allowed
to post to public stream #72
+ Fix Applied: Limit files access only to the group you're invited in
#74
+ Fix Applied: Block access to direct stream massage for user with
limited access #76
+ Fix Applied: Limit download access for limited access user #74
- Fix Applied: Update package header description
- Fix Applied: Update author header
+ Feature: Added translation to blog.edit.php
+ Feature: Translated new user registration to Estonian
+ Fix: account stuff (main menu active linl + JS enable/disable)
+ Fix: new group info page (group.first.create) is shown only for group
creator