Rename hook_ to HOOK_ to identify the part of the function name needing change

From https://drupal.org/node/2240119

# Problem/Motivation

For new module developers hooks are a bit confusing to figure out how they work. One helpful bit is when the hooks show _FORM_ID_ or THEME_ the identify the parts of the hook that need to be changed for your module or theme.

# Proposed resolution

Id propose making all the hook_ to HOOK_ to promote this visual modifiable part of the identifier throughout core.

## Before:

`hook_entity_type_alter`

## After:
`HOOK_entity_type_alter`

# Remaining tasks

Discuss any drawbacks.
Create a meta and add to coder review.