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.