Cloudcracker integration

This pull request adds a Rex library and a plugin to interface with moxie's CloudCracker hash cracking service.

<pre>
bperry@bperry-rapid7:~/work/brandonprry_msf$ ./msfconsole 

 ______________________________________________________________________________
|                                                                              |
|                   METASPLOIT CYBER MISSILE COMMAND V4                        |
|______________________________________________________________________________|
      \                                  /                      /
       \     .                          /                      /            x
        \                              /                      /
         \                            /          +           /
          \            +             /                      /
           *                        /                      /
                                   /      .               /
    X                             /                      /            X
                                 /                     ###
                                /                     # % #
                               /                       ###
                      .       /
     .                       /      .            *           .
                            /
                           *
                  +                       *

                                       ^
####      __     __     __          #######         __     __     __        ####
####    /    \ /    \ /    \      ###########     /    \ /    \ /    \      ####
################################################################################
################################################################################
# WAVE 4 ######## SCORE 31337 ################################## HIGH FFFFFFFF #
################################################################################



       =[ metasploit v4.4.0-release [core:4.4 api:1.0]
+ -- --=[ 911 exploits - 494 auxiliary - 150 post
+ -- --=[ 250 payloads - 28 encoders - 8 nops

msf > load cloudcracker

 _____ _                 _ _____                _             
/  __ \ |               | /  __ \              | |            
| /  \/ | ___  _   _  __| | /  \/_ __ __ _  ___| | _____ _ __ 
| |   | |/ _ \| | | |/ _` | |   | '__/ _` |/ __| |/ / _ \ '__|
| \__/\ | (_) | |_| | (_| | \__/\ | | (_| | (__|   <  __/ |   
 \____/_|\___/ \__,_|\__,_|\____/_|  \__,_|\___|_|\_\___|_|   
                                                              
                                                              
                                                       _      
                             ____                     (_)     
                            / __ \ _ __ ___   _____  ___  ___ 
                           / / _` | '_ ` _ \ / _ \ \/ / |/ _ \
                          | | (_| | | | | | | (_) >  &lt;| |  __/
                           \ \__,_|_| |_| |_|\___/_/\_\_|\___|
                            \____/                            
                                                              

[*] CloudCracker integration has been activated
[*] Successfully loaded plugin: cloudcracker
msf > create_cloudcracker_job -t hash -f /home/bperry/passwords -e bperry.volatile@gmail.com -d english -s 12672 -m cryptmd5
[+] Job reference ID: cryptmd5-test-70a6b1d8f30bbb99785460ab6984637f
msf > get_job_status cryptmd5 cryptmd5-test-70a6b1d8f30bbb99785460ab6984637f
[*] 	Status:		0
[*] 	Time Elapsed:	0
[*] 	Results:	No results
[*] 	Progress:	0.0
msf > create_stripe_payment -c 4242424242424242 -s 123 -e 12/2012 -j cryptmd5-test-70a6b1d8f30bbb99785460ab6984637f -f cryptmd5
[+] Payment accepted, your job will begin shortly and will take an hour or two.
msf > get_job_status cryptmd5 cryptmd5-test-70a6b1d8f30bbb99785460ab6984637f
[*] 	Status:		3
[*] 	Time Elapsed:	0
[*] 	Results:	$1$FiR/eF1A$x79HZMrX8DeOsYZ58IZtY.:TEST PASSWORD!
[*] 	Progress:	100.0
msf > exit
bperry@bperry-rapid7:~/work/brandonprry_msf$
</pre>