[#81586610] Initial basic asset rack implementation

Sets up the basic framework, and the well_proxy for
subsequent extension.
[housekeeping] Detect when no printer specified
[housekeeping] Remove duplicate code
[housekeeping] Correct indentation
[housekeeping] Improve stock plate lookup
Merge branch 'next_release' of github.com:sanger/sequencescape into 81586610_ss133_-_model_racks_of_strip_tubes_for_x10_library_preparation
[#81586610] Can find wells by locations

Horrible increase in complexity here, with little
in the way of flexibility. Might be that switching
to just having 12 map locations would be better?
Merge pull request #936 from JamesGlover/81586610_ss133_-_model_racks_of_strip_tubes_for_x10_library_preparation

81586610 ss133   model racks of strip tubes for x10 library preparation