Add PageStore.getPages which fetches a list of pages in one SVN
repository request. The request is made using SVNKit's
SVNRepository.checkoutFiles method.

No SVN attributes or version information on each page is returned by
this method.

This method is intended to be used by macros that fetch a large number
of pages but do not require SVN attributes or version information about
each page.

https://bugs.corefiling.com/show_bug.cgi?id=43036
Change signature of PageStore.getPages() to use the Collection instead of
List interface.

https://bugs.corefiling.com/show_bug.cgi?id=43036
Change signature of BasicSVNOperations.getFiles to take a Collection of
paths instead of a List.

https://bugs.corefiling.com/show_bug.cgi?id=43036
Add comment to getPages docs noting the nondeterministic ordering of the
fetched pages.

https://bugs.corefiling.com/show_bug.cgi?id=43036
Remove unused imports.
Merge remote-tracking branch 'pwc/bug43036'
Improvements to fix for: https://bugs.corefiling.com/show_bug.cgi?id=43036

getPages does now set the attributes expected elsewhere, and the
underlying getFiles can nearly be used as a drop-in replacement for
getFile.