box: add support for blacklisting/excluding jobs

The new --exclude-pattern improves the existing --include-pattern
by allowing users to prevent a particular job from running even
if it was included by the include pattern.

Typical intended use case is to explicitly remove certain job
or jobs (such as suspend jobs) while using broad include masks
such as "*" or a whitelist.

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
"[r=sylvain-pineau][bug=][author=zkrynicki] automatic merge by tarmac"