remove DeltaVision-specific constant from pixels service
create new disk usage request
implement new disk usage request
make new request callable

(add thumbnail service into request object factory registry)
adjust API of disk usage request
adjust disk usage implementation to match API change
extend disk usage object with file counts
implement file counts for disk usage requests

refactors usage tracking to fit extra duties
Support show=image-1|image-2
New OmeroWeb/test for show=project-1|project-2
Fix flake8 errors
Fix flake8 errors
initially_select always == initially_open if first_object 'well'
Merge remote-tracking branch 'remotes/origin/develop' into trac-7240-disk-usage-count
Web test_show tests multiple wells

Selection of multiple wells is not currently supported
but we test that at least the first well is selected and
shown, while the second well is ignored.
Update develop submodules

Repository: openmicroscopy/openmicroscopy
Already up-to-date.

Repository: openmicroscopy/bioformats
Updating 8cbf2c3..1ab84ee
Previously merged:
  # PR 1279 rleigh-dundee 'travis: Build with Oracle JDK 8'
  # PR 1290 rleigh-dundee 'cmake: CompilerChecks: Correct standard warnings'
  # PR 1268 carandraug 'multiple netpbm fixes'
  # PR 1285 sbesson 'Fix Memoizer.getMemoFile(id) when directory is the root path'
  # PR 1286 melissalinkert 'Fix declaration of ConcurrentHashMap instance (rebased onto develop)'

Repository: ome/scripts
Already up-to-date.

Repository: openmicroscopy/ome-documentation
Updating aba2451..c4f65a9
Previously merged:
  # PR 963 hflynn 'Moving walkthros up a level in TOC'
  # PR 958 hflynn 'Delete OMERO tools build info'
  # PR 954 sbesson 'OMERO developer setup '
  # PR 953 mtbc 'tweak server docs (rebased from dev_5_0)'
  # PR 955 hflynn 'Tidying up location of git info'

Generated by OMERO-5.1-latest-submods#182 (http://ci.openmicroscopy.org/job/OMERO-5.1-latest-submods/182/)
Merge pull request #2912 from jburel/java8

Java8
Merge pull request #2975 from jburel/jdk1.8-nobootclass

Jdk1.8 nobootclass
Fix flake8 errors
Add setup.cfg at the root of omeroweb/ source directory

Adjust Travis build to use this setup.cfg instead of testing individual
folders.