Only send final PUT on Azure profiles

Fix core dump when reading Azure key from environment variable

Improve interface between mod_http_cache and storage providers

Remove debug

Remove out-of-date TODO

Add new configuration to example

Changes arising from Christopher Rienzo's comments

Add function to pointers to the profile to allow for better integration with the storage providers.

Add function to pointers to the profile to allow for better integration with the storage providers

Remove old header file inclusion