jsgui: Bind to input events rather than change+keyup

Event fires when text is pasted from mouse.
jsgui: Reword property-reload button

We're not necessarily only reloading brooklyn.properties - the optional
--localBrooklynProperties will also be reloaded.
Merge pull request #1288 from sjcorbett/jsgui-yaml-paste

Bind to input event rather than change+keyup