Only 'setContent' from watch if content differs

[garhbod]

Fixed the watch function to prevent the cursor from jumping to the start of the editor content every time the content is changed. See issue #4

Also made id property optional with a unique id set if it doesn't exist And made content property redundant by pulling the value into the setContent on init. I have left it in so that current installs don't break but it isn't really needed anymore