Load BODAAC configuration from metadata
Update BodaacDownloadHandler.js
Use download format constant.

Removed unused variable.
DownloadController no longer uses Layer to retrieve information.
BodaacDownloadHandler no longer passes-on layerId
BodaacDownloadHandler no longer passes-on serverUrl
Moving the usage of downloadFilename from ProxiedRequest to RequestProxyingController.

This was causing problems because there were values in params (namely 'downloadFilename') which were being included in the external URL but which were only intended for the Portal to use. Geoserver was balking when it got query string parameters it doesn't know about.
Handle exceptions in the external request when trying to download source NetCDF files.

Also removed paramater values from 'params' as we used them so they weren't also forwarded on with the external URL.
Whitespace
Remove 'format' from params when it is used
Improve Server-finding code
Merge pull request #1277 from aodn/BODAAC_from_metadata

BODAAC from metadata
Hides download button and adds message when download estimator calculates Zero bytes
Remove common function _downloadUrl and use inheritance to override behaviour.
Removing unnecessary constructors
Remove unused function
Download handlers can now be asked if the know how to estimate the size of a download.
Add download estimation behaviours to BodaacDownloadHandler
Rename download estimate function
Update DownloadEstimator to use new functionality in DownloadHandlers