Update DropBox documentation

A minor change to make a couple of sentences more grammatical.
Merge pull request #814 from bpindelski/ldap_errors

Add LDAP error message explanation.
Merge pull request #816 from will-moore/rebased/develop/webgateway_mip_5150

Webgateway mip 5150 (rebased onto develop)
Fix description of upgrade jobs
Merge pull request #812 from sbesson/50_job_renaming2

Remaining changes post 5.0.x job migration
Merge pull request #817 from ximenesuk/rebased/develop/patch-1

Update DropBox documentation (rebased onto develop)
merge develop -D org: PR 799 (Linux walkthrough (rebased onto develop))
merge develop -D org

Repository: openmicroscopy/ome-documentation
Updating 1f51804..6e003c4
Merged PRs (fast-forward):
  # PR 817 ximenesuk 'Update DropBox documentation (rebased onto develop)'
  # PR 812 sbesson 'Remaining changes post 5.0.x job migration'
  # PR 816 will-moore 'Webgateway mip 5150 (rebased onto develop)'
  # PR 814 bpindelski 'Add LDAP error message explanation.'

Merged PRs:
  # PR 799 manics 'Linux walkthrough (rebased onto develop)'

Generated by OMERO-5.1-merge-push#266 (http://ci.openmicroscopy.org/job/OMERO-5.1-merge-push/266/)