add 'options' config parameter to compression streams

This adds an additional parameter called 'options' that
will add user configurable options to a compression command.
This addresses LP:1168507 as well as being a more general
solution for gzip --rsyncable introduced as a separate
'gzip-rsyncable' method in holland 1.0.8.

Example:
[compression]
method = gzip
level = 1
options = --process 4 --rsyncable --verbose
cleanup stderr logging from compression commands

Previously all stderr was output as 'Compression Error: <line>'
but this is not accurate if a user option simply specifies --verbose
for instance.  This change logs at the error level if the compression
command exited with non-zero status, and at 'info' if it
exits successfully.
rename LOGGER -> log in holland.lib.compression for consistency

The rest of holland uses LOG for the global module logger, but
compression still used a different semantic from ancient history
use TemporaryFile rather than pipe for stderr

stderr can overflow a pipe buffer and lead to deadlocking. With
the configurable compression commands this is more likely
particularly when using options like --verbose.

Notably this change does introduce an additional potential failure
case if there is an io error on the temporary file (ENOSPC, etc.)
but this is likely to cause the backup to fail anyway.
fix lp:1186992

Always wrap stream operations in a try ... finally block so we ensure
fileobj.close() is called.  This also ensure IO errors when opening
the stream are handled consistently between file-per-database modes.
Merge branch 'lp_1186992'
Merge branch 'master' into lp_1168507
Merge branch 'lp_1168507'
use the current redhat release for the default mock target

uses epel-$release-x86_64 by default, where release is
obtained from the major number in /etc/redhat-release
support compression.options in pgdump plugin as well
Merge branch 'lp_1168507'