Bug 34456: Add the ability to download a template rendered report as a file

Bug 34456: Add the ability to download a template rendered report as a file

Bug 34136 adds the ability to render a report using a notice template rather than displaying data in a table. It would be even more useful to be able to download the contents as a file where the notice subject can be used as the filename so the filename can be generated dynamically ( such as adding the current date as part of the filename ).

Test Plan:
1) Follow the test plan for Bug 34136
2) Run your report
3) Note under the Download menu the new item "Download as" with the
   subject line for your template
4) Click that link, note the file contains the contents of your report!

Signed-off-by: Sam Lau <samalau@gmail.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>