[NEXUS-6107] Use plexus-utils forceMkdir() to remain compatible with java6
Merge pull request #236 from sonatype/NEXUS-6107-mkdirs-java6-compat

REVIEW: [NEXUS-6107] mkdirs java6 compat
Merge branch 'nexus-2.7.x' into NEXUS-6004-composite-supressed-exceptions