fix alphabetization of data types in repo home page

[olbris]

When you go to the DVID landing page for a repo, the data instances are alphabetized grouped by data type (which is good). However, the data types seemed to be alphabetized into two seemingly arbitrary groups. Eg, imagetile and labelblk precede annotation, keyvalue, and labelvol. Can we get them alphabetized all together?

[neomorphic]

They are ordered that way on purpose, so that all the items that can be used in the tile viewer and neuroglancer are at the top of the list. Makes it easier to pick one without scrolling if there is a long list.

[DocSavage]

If there were a line between the data types for tile viewing and the others that are alphabetized, it might be more obvious how the data instances are listed?