manage command for moving attachments to S3

This is a one-time operation, which is why some stuff is hard-coded and doesn't come
with tests.

All it's doing is going through every attachment in the database that the PMT has
stored locally and shipping it up to the configured S3 bucket, using the same
path/filename scheme that we've established elsewhere. Then it updates the db
entry with the new S3 URL.

Once this goes out to production, I will rsync the uploaded attachments from hutz
(where the PMT lives) to the /mnt/nfs/applications/dmt/attachments/ directory,
then run './manage.py move_attachments_to_s3 --settings...' and that should
be that.

Once everything has been moved up and verified, I'll delete this command
since there will no longer be any use for it.
Merge pull request #83 from thraxil/attachments-to-s3

manage command for moving attachments to S3
move to s3 command has been run, so it's no longer needed
Merge pull request #85 from thraxil/remove-move-to-s3-command

move to s3 command has been run, so it's no longer needed
delete milestone

only empty milestones can be deleted. (otherwise, we'd have to figure
out what to do with the items in the milestone, since we don't like to
lose history)
Merge pull request #87 from thraxil/delete-milestone

delete milestone
create group. PMT #95448
Don't allow untitled or duplicate groups
resolved items report

OK, a pet peeve of mine is when items sit in the RESOLVED state forever.
I don't understand why, but some people like to assign lots of tasks
to other people and then when they get resolved, they take their
sweet time to verify them.

This is a very simple report to name and shame.
Updates django-bootstrap-form for bootstrap 3 compat and better forms
Use forms.ValidationError instead of ValueError on project create form
Merge pull request #91 from nikolas/update-django-bootstrap-form

Updates django-bootstrap-form for bootstrap 3 compat and better forms
Merge pull request #89 from ccnmtl/create-group

Create group
Merge pull request #90 from thraxil/resolved-report

resolved items report
Merge pull request #92 from nikolas/use-forms-validationerror

Use forms.ValidationError instead of ValueError on project create form
Add Active Projects report