plainbox: bump copyright

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
plainbox: bump version to 0.17 final

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
"automatic merge of lp:~zkrynicki/checkbox/plainbox-0.17/ by tarmac [r=zkrynicki][bug=][author=zkrynicki]"