Fix cmd_threads

MSP-9006

Fix cmd_threads for all options and add specs for handling of each
option.  Additionally, improve the tab completion to allow for multiple
compatible options to be completed at once instead of only allowing one
option and argument.
Merge branch 'bug/msfconsole-boot' into bug/cmd_threads
Merge branch 'feature/module-cache-construction' into bug/cmd_threads
Land limhoff-r7/metasploit-framework#10

Fixes cmd_threads

Jira story: MSP-9006