Remove hash after the url when clicking Meta Data

Removes that hash appended to the URL when clicking Meta Data in post settings.

Closes #4386

When clicking 'Meta Data' the click event appends a # to the URL. I replaced the a with a button element so that won't happen anymore. The button has a type attribute because it will try and submit the form without it. Added text-align: left to the navlist button because the button centers it's content by default.
Merge pull request #4405 from jillesme/iss-4386

Removes hash after the url when clicking Meta Data
Adds SIGTERM handling

closes #4403
- adds SIGTERM handler to match SIGINT handler
Merge pull request #4404 from Haegin/add-sigterm-handler

Adds SIGTERM handling