create release branch sim-ns3-3.11.0-branch
update travis url

Conflicts:
	README.md
add SCTP support (without HMAC support)
handle SCTP non-blocking socket during connect()

 DCE has no struct file in struct socket: fake it for nonblocked sctp_connect()
fix gen_crc32table build
more fix on crc32table.h
fix inappropriate queue_delayed_work() handling: timer never fired.
add travis CI
change optimization option
 avoid infinite loop in memset() of lib/string.c
add gcc version check for optimization option
handle SOCK_CLOEXEC appropriately for socket()
remove dce-umip-dev module for default bake configuration
enable TCP cc variants by default
Merge remote-tracking branch 'dce/sim-ns3-3.11.0-branch' into
mptcp_v0.88
first commit