pathogen: revert to older version for CentOS 5.

Due to what is presumably a bug in CentOS 5's Vim, Vim segfaults if
pathogen's commit 91e6378908721d20514bbe5d18d292a0a15faf0c is present
and any bundles are present.  Revert to an older version to work around
this.  This is pathogen issue #136.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>