Output send on post requests is base64 encoded

Plugins need to receive ascii encoded strings and requests was encoding
using unicode on some cases. Now is b64 encoded so we should be ok.
Fix on several plugins and test cases added

Plugins fixed:
        nessus
        w3af
        openvas
        netsparker
(Basic) Test cases added for:
        nessus
        w3af
        netsparker
Preserve original command on user history

If a user types "nmal localhost" and we change that command because of a
plugin, we want to keep the original command on user history.
That way Faraday is more transparent to the user
Ctrl + C handling

Clean exit on ctrl + C
Printing information when exiting

Just a message to the user when ctrl C is pressed
Important fix on managers.all

time module used but not imported, so every FS worskpace was throwing an
exception
Merge branch 'hotfix' into integracion

Changes merged into integracion:

Not while true while waiting for next zsh command
Base64 encode on command line api message
plugins fixes
Control C interruption handler
Important fix on create workspace

A missing import was making impossible to create a workspace using the
UI
crud test cases for integration
adding assertion for creation
pylint fixes
Creating workspace swtiching testcases
Adding workspace removal testcases
Merge branch 'integracion' of git.assembla.com:faraday into integracion
Moving setup to setupclass
Merge remote-tracking branch 'origin/integracion' into merge
Release notes for the new version

Bugfixes:
    Workspace wouldn't create. Silly missing import.
    Another missing import... ups!
    Some plugins fixes

Features:
    ZSH History rewrite
    Commands forwared with base64 encode
    Removal of nasty busy waiting