change for centos "ip link set master" to "brctl"
if ip link set is failed, then try brctl addif.
Merge remote-tracking branch 'upstream/master' into for-centos

Conflicts:
	pipework
rebase master
Merge pull request #14 from WhiteAnthrax/for-centos

Fallback on brctl if "ip … set master" fails (for CentOS).
Allow to specify containers by name instead of by id (closes #21).
Document Docker integration and VirtualBox networking issues.
Return 0 if everything went fine

Without this, pipework will return the exit status of the last command
which is [ "$IPADDR" = "dhcp" ] or [ "$GATEWAY" ] in this case
Merge pull request #23 from discordianfish/fix-return-code

Return 0 if everything went fine
Added optional parameter '-i <ifname>' to set container interface to set up with pipework
- I tried to not brake any prior usage of pipework so these changes might be suboptimal
Removed verbose output
Merge pull request #25 from lukaspustina/master

Adding -i <ifname> to specify network interface to manipulate inside container
Revert the funky MAC address and gateway parsing.
Avoid race condition when setting default gateway.
If ip link set is failed, then try brctl addbr.
Merge pull request #31 from johngmyers/default-route-race

Avoid race condition when setting default gateway.
Merge pull request #32 from hansode/for-centos6

If ip link set is failed, then try brctl addbr.
Set BRTYPE to "linux" by default.

If the bridge doesn't exist, `BRTYPE` wasn't set, and the code to
add the interface to the bridge was never called.

Set it to `linux` by default.
Merge pull request #1 from jpetazzo/master

Pull from head