Wrap folder names in folder list view

It is impossible to predict what system a user may choose for creating and labeling subfolders.  It is also impossible to predict an upper limit for the maximum folder path length and/or subfolder depth that a user may use.  Therefore, it makes no sense to hide part of a folder path (beginning or ending) with ellipsis on the assumption that the hidden part is unimportant for distinguishing one folder from another when viewing a long list of folders.

This problem was originally brought up in <a href="https://code.google.com/p/k9mail/issues/detail?id=1911">Issue 1911</a>.  (The original issue complained of the ellipsis at the end of the path.  The ellipsis was later moved to the beginning of the path, but that didn't really improve the situation.)

This (trivial) patch:

1) Permits folder names to wrap on multiple lines in folder list view so users can see the entire name.

2) Reduces the default font size used in folder list view to a reasonable size so that long folder paths wrap to fewer lines.

Ultimately, the implementation of a hierarchical folder list as discussed in Issue 17 would be a better solution.  But in the interim, this patch is an improvement over the current implementation.