Use conn.SERVICE_OPTS in well_images()

[will-moore]

See #270

To test:

• Browse to a Well in your non-default group
• Open-with iviewer. URL is e.g. iviewer/?well=101
• Should see images in the well etc instead of "No image data"
• Also can confirm directly that /iviewer/well_images/?id=101 shows the correct response.

[mtbc]

This isn't working for me at all in Firefox or Chromium, I just get a blank tab (with a correct title) and TypeError stuff in the JavaScript console.

[will-moore]

Something else is broken - need to investigate when I'm back.
But I think this PR is working: e.g. user-3 for well https://merge-ci.openmicroscopy.org/web/webclient/?show=well-11014 - this works: https://merge-ci.openmicroscopy.org/web/iviewer/well_images/?id=11014

[will-moore]

The error should be fixed with 7e894df in #264.