Only attempt email link sign-on if tokens exist

If the `view.php` page is requested and an auth token is not present in the
URL, do not attempt to sign the user on since it will always fail and will
result in a false "Failed login attempt" warning to the system log.
Once you are authorized, you should be authorized forever.
Merge pull request #765 from thegrandpoobah/fixrefreshbutton

Reviewed-By: Peter Rotich <peter@osticket.com>
Merge pull request #763 from greezybacon/issue/unknown-user

Reviewed-By: Peter Rotich <peter@osticket.com>
file: Don't crash when sending data to file backends
Inline images in email without a 'cid:' indicator

It is the defacto standard to reference an inline image in an email by
referencing the Content-ID header of the referenced attachment in the @src
attribute of the image. For instance, `<imc src="cid:image001.png">` where
the `cid:` scheme of the attribute indicates that the referenced image URL
is a separate content of the email. The image attached to the email would
have an accompanying header like: `Content-Id: <image001.png>`. However,
some mail systems, including a certain fax to email service, do not
correctly indicate the location of the image with the content-id URL.
Instead, the referenced image tag would be `<img src="image001.png">`

This patch addresses the issue by searching the message body for all
references to attached content-id's in all @src attributes with or without
the content-id URL scheme indicator. Previously, such images would not be
displayed inline in the ticket thread.

References:
https://tools.ietf.org/html/rfc2392
Merge pull request #779 from greezybacon/issue/inline-img-missing-cid

Inline images in email without a 'cid:' indicator

Reviewed-By: Peter Rotich <peter@osticket.com>
Merge remote branch 'upstream/develop' into develop-next

Conflicts:
	view.php