[cacerts] Added cwd to copy from omnibus cache rather than where fetcher tries to unpack it

There is a bug in omnibus-ruby that may or may not have been fixed. Since the
source url does not point to an archive, omnibus-ruby tries to copy cacert.pem
into the project working directory. However, it fails and copies to
'/var/cache/omnibus/src/cacerts-2012.12.19\' instead There is supposed to be
a fix in omnibus-ruby, but under further testing, it was unsure if the fix
worked. Rather than trying to fix this now, we're filing a bug and copying the
cacert.pem directly from the cache instead.
[libpng] Updated url for libpng for 1.5.15
[nagios] Use Sourceforge mirror autoselector instead of hardcoding a specific mirror
[openresty] Added openresty build based upon nginx.

Added an openresty build definition. It should be a drop-in replacement
for standard nginx.

 - Since openresty is a metapackage, its configure script descends into
   the source files and calls `configure` for nginx. In order to link to
   the embedded shared libraries, we added linker and cc flags to force a
   lookup in the embedded directories first

 - The sbin and nginx.conf had to be explicitly set to the omnibus
   convensions.

 - Openresty cookbook will automatically detect AIO capabilities and
   automatically enable AIO compile flags. It appears that Ubuntu 10.04
   have the necessary kernel version. However, this requires compiling
   additional AIO libraries. This is a possible improvement for future
   builds.
[zlib] Use Sourceforge mirror autoselector instead of hardcoding a specific mirror