Advanced Search - Case Pane: Can not clear All Cases / My Cases radio button once it's selected

(Reported by lcdweb on IRC)

BUG: If user has "all cases" permission, the "All Cases" option on the case_owner radio button is automatically checked when the Cases pane is clicked open. If the user does a search with other radio option and then clicks "clear" and searches again, the "My Cases" option is re-checked and the search continues to use that critieria. There is no way to actually NOT use that criteria other than reloading the Adv Search form via reset=1.

Fix implementation:
1. Fix the bug above - if case_owner has been cleared and no other case criteria are selected, we should not "recheck" case_owner, we should not include any case criteria in the search, and the Cases pane should be closed when search results return.

2. Remove the code which automatically selects "All Cases" when the Cases pane is opened. We don't automatically select criteria fields when other panes are open - so this is inconsistent. It's also confusing, since the user needs to notice that and alter or clear if they don't want to use that criteria. Replace this with code which selects the default "All Cases" if neither of the "case_owner" buttons is checked when user selects a Case Type, Case Status or Deleted Cases checkbox (i.e. make sure one of the case_owner options is checked if we're going to search on cases).

3. Modify case_owner labels and swap their order to clarify their purpose:
[ ] Search All Cases [ ] Only My Cases