first init
1. use post_subrequest handler to create new subrequest
2. use set_header_handler to change range /content_length header
3. waiting for all output been sent of the main request before create subrequest
1. fix bug :alert non-active request  by create subrequest of current reqeust rather than the r->main request
refine codes
remove unused codes
fixbug: hang request if the upstream DO NOT support range request
README
Fix:
 1. segmentfalut when parse content-range
 2. can not send the last content in subrequest for small content-length
 3. duplicate subrequest when we just need one subrequest
Merge remote branch 'origin/master'
fix bug
fix refcount overflow
Add README content
Fix to support HTTP1.0
Fix to only support GET/POST
Change request sequence number start from 1
Add version info
Fix NGX_AGAIN case : create subrequest after NGX_OK(not NGX_AGAIN)
process case of '0-' range request
update version
fix: do not process range request which absents start boundary
Fixbug: hang request sometimes