Bailout when no web-password was given, while trying to configure a ganglia server and bypass invalid web-user values.

cr https://cr.amazon.com/r/1628766/
Fix ganglia cookbook plugin system and layer awareness.
Typo on error message
fix typos on ganglia plugin paths
Replace special characters to generate cluster name, as ganglia doens't support many non-words characters for this purpose.
Reimplement handling of rubygems by monkeypatching Chef's chef_gem, gem_packege resources and the rubygem proovider.  Use bundler environment and install rubygems in the right location. Added tests.
Ganglia cookbooks:
* Remove obsolete files
* Fix module link and permissions
chef_gem should process given installation options
Merge branch 'master-chef-11.4' into fix-ganglia-chef_11.4
Fix stop ganglia client conditional
Fix rails app deployment test
fix typo in value_for_platform_family list
fix handling of ganglia python modules directory.
change yum.conf instead of replacing it
make the list of PHP packages that we install configurable so that customers can override them via attributes
Enabling a mount point (i.e. writing /etc/fstab) does not depend on /etc/mtab entry.
Align fstab entry generation to Chef 0.9 version.
Stricter dependency flow to avoid race conditions between blkid and mkfs.
Rakefile: platform_family is a known attribute
Rakefile: syntax-check all files