Utility module rather than monkey patching String

Removed the risk of clashing with other monkey patching libraries and
introducing unexpected behaviour.
Merge branch 'no-monkey-patching' into custom
Merge branch 'delete-options' into custom
Altered StringUtils to include and extend

Ensures that it is available from all potential contexts once mixed in.
Merge branch 'no-monkey-patching' into custom
Multiple minor tweaks
Merge branch 'field-uri-aliases' into custom
Merge branch 'better-errors' into custom
Added ability to batch GetItem requests
Full body for XML error responses
Merge branch 'master' into custom

Conflicts:
	lib/ews/ews_client.rb
	lib/ews/item_accessors.rb
	lib/ews/types/calendar_item.rb
	lib/viewpoint/string_utils.rb
Fixed merge error
Removed custom get_items method as can use new one
Custom hack for extracting event attendee status
Fixed build attendees users to extract attendees correctly