OOIION-1282
When a user clicks the Get Capabilities button, change the text to Getting Caps... and disable it.  When the capabilities have been loaded and rendered, change the text back and reenable it.  This prevent a user from clicking the button multiple times and ending up w/ duplicate entries in the command panel.
Merge pull request #357 from cgalvarino/getcaps-r2

OOIION-1282