Issue/2055 optimal drawer width

Fix #2055 - menu drawer is now sized based on what I could pull from the various conflicting specs :) This changes the drawer width to match that of Google's own apps.

http://www.google.com/design/spec/layout/structure.html#structure-side-nav
http://www.google.com/design/spec/patterns/navigation-drawer.html
http://android-developers.blogspot.co.uk/2014/10/material-design-on-android-checklist.html
https://medium.com/sebs-top-tips/material-navigation-drawer-sizing-558aea1ad266