More link theming function needs to pass array in class

Problem/Motivation

To replicate the problem
1. create entity reference view
2. create custom pane using entity reference view
3. add custom pane to page manager
4. view page in the browser and notice the error pointing to line 19 in gesso/includes/navigation.inc (it seems that css class was already added to pane. css class expected to be an array.

Proposed resolution

make css class view-more array

Remaining tasks

User interface changes

None

API changes

None

Data model changes

None