Explicitly set the locale on the remote calls to a POSIX format.

Prevents issues with devices in a non-US locale that might break the string-based date format.
Nest the remote calls to prevent full table reload from locking table.

When reloadTable is finished, then continue reloading the sections.  This is *not* the ideal solution since the code needs refactoring.  If the refactor doesn't make it into 4.1, this will solve the crash at least.
Merge pull request #1553 from wordpress-mobile/issue/1552-stats-crash

Stats crash when async calls update backing data during reload