piuparts_tap: explicitely set Encoding::UTF_8 for Ruby 1.9

On Debian/wheezy LANG and LC_ALL are empty by default (and therefore
defaulting to 'C' locale), running piuparts_tap therefore fails with:

| /usr/bin/piuparts_tap:26:in `gsub': invalid byte sequence in US-ASCII (ArgumentError)
| 	from /usr/bin/piuparts_tap:26:in `<main>'

The real fix would be to set LANG/LC_ALL accordingly, but we can't
control this from inside the piuparts_tap script, so let's
work around this issue by setting Encoding::UTF_8 explicitely.

Thanks: Christian Hofstaedtler <ch@zeha.at> for feedback
jenkins_debian_glue.pp: update CopyArtifact configuration

For some reason current versions of Jenkins with TAP plugin fail to
retrieve the artifacts and the jenkins-debian-glue-piuparts job fails
with:

| Unable to find a build for artifact copy from: jenkins-debian-glue-binaries
| Build step 'Copy artifacts from another project' marked build as failure
| TAP Reports Processing: START
| Looking for TAP results report in workspace using pattern: piuparts.tap
| Did not find any matching files.

The 'Parameter filters' option from the 'Copy artifacts from another
project' setting gets set to "architecture=$architecture" when using
the 'projectName' tag. By using
'jenkins-debian-glue-binaries/architecture=$architecture' inside the
'project' tag the 'Parameter filters' option is empty again and does
what it is supposed to do.