add ruby 1.9.2p330
Merge pull request #3012 from hone/ruby-1.9.2-p330

add ruby 1.9.2p330
remove the security-head note from config/known
do not check known rubies when patch is missing for 2.1.0, fix #2990, fix #3002, closes #3010
export -f rvm_debug, fix #2978
Fixed #2995 execution of 'after_cd' hooks

Problem description:

'rmv_path/scripts/hook' ( http://git.io/PwckwQ ) contains:
  hooks=( "$rvm_hooks_path")
  [[ "$PWD/.rvm/hooks" == "$rvm_hooks_path" ]] ||
    hooks+=( "$PWD/.rvm/hooks" )

  _hooks_list=($(
    __rvm_find -L "${hooks[@]}" -iname "$rvm_hook*" -type f 2>/dev/null
  ))

but when env is not loaded $rvm_hooks_path is undefined. This leads
to '${hooks[@]}' contains a space and 'find' will fail with
'find: ftsopen: No such file or directory' and tnx to '2>/dev/null'
error will be invisible.
Revert "introduce rvm_project_rvmrc_default=2 to speed up loading scripts/rvm, update #2791"

The introduced behaviour leads to skipping environment loading as result
the 'after_use' hook is not triggered afrer first rvm load.

Looks like that the original speed problem #2791 can be fixed via
creating default rvm environment

This reverts commit 5db0b1bcf4f2f5ce3f5fee388e0e2c715bc8f222.
Updated 'after_use' hook invocation.

Just to make hooks invocation identical across the project
Trigger 'after_cd' hook on rvm loading

'after_cd' should be triggered independently of '__rvm_project_rvmrc'
result