New image chooser class. [1825]

This new chooser is essentially just a copy of the existing
AddeImageParameterChooser. The key difference is that it creates an IDV
data source rather than McV's AddeImageParameterDataSource.

Also I'd like for it to eventually include the ability to wait until the
"absolute times" tab is visible before attempting contacting the server.

(i know there is an inquiry for that, but I can't recall the number)
Clean copy of AddeImageDataSource. [1825]

My intent is to use this mostly for logging and testing purposes and
then remove it.
Make SIZE_THRESHOLD public rather than private.

[1825]
Override doLoadInThread. [1825]

This overrides the doLoadInThread in McV’s AddeImageChooser in an
effort to pass in a valid “allBands” property to the IDV’s
AddeImageDataSource.

This also required a change in readTimesInner method in McV’s
AddeImageChooser to make sure that the field behind the allBands
property was populated correctly.