Updated the bundled Google Maps block

Added Google Places Auto-complete support within the blocks management
form
Updated the UI to look more 'bootstrapy'.
Removed server-side geo-coding.
Added map canvas width & height options (default to 100% width by 400px
height to maintain compatibility)
Refactored the JS slightly as per @mkly's request
Defaulted width & height columns within the DB schema to allow
consistent upgrade
Added additional prompt to form validation if the lat & lng are not set
Tweeked the location fields description text on the block editing form