C++11 std::shared_ptr fixes:

Test for C++11 std::shared_ptr was always failing because std::make_shared was
calling a constructor of 1 argument which did not exist for the struct A. Changed
test code snippet to call default no argument constructor of A.

Once C++11 std::shared_ptr support was fixed, contentDispositionField.cpp and
contentTypeField.cpp would not compile because std::shared_ptr cannot be implicitly
cast to bool (i.e. in a return statement). Added explicit cast to bool.
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
IMAPMessage::processFetchResponse was attempting to set Cc and Bcc header fields to values of type mailboxList.
HeaderFieldFactory registers these fields as type adddressList, so a bad_field_value_type exception was
thrown when processing a fetch response for a message with either Cc or Bcc fields.

Fixed by calling toAddressList on the mailboxList header field values to convert them to expected type.
Merge remote-tracking branch 'upstream/master'
Merge pull request #66 from tholdawa/master

Fix IMAPMessage::processFetchResponse bad_field_value_type for Cc and Bcc fields