Fix surt browse

[ldko]

This is to fix #114 and #115.

• Regarding Nominating an URL length 255-300 chars responds with a 404 #114: A user can nominate URLs of up to 300 characters in length. When nominating a URL, a surt attribute is created to hold in value a SURT form of the URL. The SURT form of an URL can be a few characters longer than the URL, so this PR increases the allowed length of value to 305 to accommodate the longest URLs' SURT forms.
• Regarding Surt browse for TLDs may return out-of-scope results #115: on a project's url listing page, top level domains are given as links to a listing of URLs matching the SURT prefix of the top level domain. The SURT prefix, should end in a comma, but the way we are using the top-level domain in our browse structure and with how we are displaying the link text, we don't look up SURT values currently with the comma which causes matches for .co to include .com etc. Adding a comma to the template link allows for going to the correct SURT prefix for the view.

ping @clarktr1 @somexpert this is ready for review

[somexpert]

This all looks good to me! 👍

[clarktr1]

👍