Fix table name typo
Merge remote branch 'upstream/develop' into develop
Make captcha text case-insensitive
Better email headers for In-Reply-To and References

Previously, the References header emitted by the system for new thread
entry auto-responses and alerts included the message-id for which the email
was a reply in the `References` header. This patch corrects the issue by
placing the reply message-id in the In-Reply-To header, and constructs a
correct References header.

That is, if available, the References header received in the email that was
used to create the thread entry is appended to the message-id the email is
actually in reply to. This is the expected usage of the References header.
Disambiguate Reply-To from In-Reply-To mailer opts

Previous the options defined for the Mailer::send() function were confusing
when sending an In-Reply-To header
Merge pull request #823 from protich/issue/captcha-case

Make captcha text case-insensitive

Reviewed-By: Jared Hancock <jared@osticket.com>
Merge pull request #825 from greezybacon/issue/better-email-references

Better email headers for In-Reply-To and References

Reviewed-by: Peter Rotich <peter@osticket.com>
Content disposition parameters are optional

If a Content-Disposition header exists for an attachments, it isn't required
to have any parameters (like a file name)
Merge pull request #828 from greezybacon/issue/maybe-dparameters

Content disposition parameters are optional

Reviewed-By: Peter Rotich <peter@osticket.com>
Use system date format for datepicker

Previously the American date format (m/d/Y) was used exclusively for
formatting dates in the datepicker widget. This patch enables the widget to
be formatted based on the format set in the admin panel.

Fixes #829
Merge pull request #830 from greezybacon/issue/datepicket-date-format

Use system date format for date picker

Reviewed-By: Peter Rotich <peter@osticket.com>
Add long lost kb category listing background
Merge pull request #831 from greezybacon/issue/kb_background_bg

Add long lost kb category listing background

Reviewed-By: Peter Rotich <peter@osticket.com>
Update release notes for v1.7.3

And freshen up the upgrading guide