reporter-rhtsupport: upload file to BigFileURL if it is large

This patch adds BigFileURL and BigSizeMB parameters.

If uploaded DIR is bigger than BigSizeMB, then it is not attached
to the case, but uploaded to BigFileURL, then a comment is added
to the case with the URL of uploaded file.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Martin Milata <mmilata@redhat.com>

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>