Weekly Fixes and Improvements

This weeks fixes and improvements:

fixed a bug that was causing the "duration" field in the edit event dialogue to appear empty.
added tooltips to fields in the settings to make it easier to understand what each field is/does.
updated some of the activity feed icons to make it look better.
updated the default notification setting to "on" (so whenever a new client/cleaner is created they will get notifications UNLESS you turn it off)