Enable transferring of attribute using command 'repo manifest -o -'

'upstream' attribute is now transferred to the new manifest xml
that is created when using command 'repo manifest -o -'.

Manifest help is updated for the attributes 'sync-c','sync-s' and
'sync-j'.

Bug: Issue 164
Change-Id: If63f781e91d25c5b5b5ea0696b0c04337b0a686a
2 files changed