External MWI core support.

* The core external MWI resource provides for MWI message counts
persistence using sorcery.  With sorcery, the user is able to configure
which sorcery wizzard backend to use if the default astdb is not desired.

* The core external MWI resoruce provides some debugging CLI commands
enabled by defining MWI_DEBUG_CLI.

The debugging CLI commands are:
"mwi delete all",
"mwi delete like <regex>",
"mwi delete mailbox <mailbox>",
"mwi list all",
"mwi list like <regex>",
"mwi show mailbox <mailbox>", and
"mwi update mailbox <mailbox> [<new> [<old>]]".

(closes issue AFS-43)

Review: https://reviewboard.asterisk.org/r/3061/
........

Merged revisions 404952 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@404953 f38db490-d61c-443f-a65b-d21fe96a405b
External MWI AMI support.

The external MWI AMI interface provides a thin wrapper around the core
external MWI resource.

The resource adds the following AMI actions:
MWIGet,
MWIDelete, and
MWIUpdate.

(closes issue AFS-46)

Review: https://reviewboard.asterisk.org/r/3061/
........

Merged revisions 404954 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@404955 f38db490-d61c-443f-a65b-d21fe96a405b