Download panel frontend changes to allow estimation of file size
Added proxying package
Created new class ExternalRequest and made ProxiedRequest a subclass
Correcting class for Loggers
Only ProxiedRequest should need to deal with params
Rename `proxy()` in ExternalRequest as it doesn't make sense in that context
Added ProxiedRequest tests

Including some changes to ProxiedRequest and ExternalRequest
coding conventions fix
Tests for ExternalRequest
displaying motd with mocked isLandingPage() function
probing for landing page before display of MOTD
Changes made as per review
fixes #763
added check if spatialConstraintcontrol exists
Changes to lang file
re-instate colour to results headers
fixes #773
Merge pull request #783 from aodn/resultsHeaderBackgroundColour

Re-instate colour to results headers
reworked dummy def to estimate size
much simpler way of probing the landing page