new directive 'compressionlevel'

Default compression level now changed to Zlib's default (was 'best_speed')

Obtained from: Stephen Pierzchala <stephen@pierzchala.com> Michael Schroepl <Michael.Schroepl@telekurs.de>
Reviewed by:  Ian Holsman


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@98895 13f79535-47bb-0310-9956-ffa450edef68