encode the @ symbol on endpoint username fields

• User impact:

  Medium
• Affects Docs:

  Yes
• Similar Issues:

  None

Right now if you have a user name that is an email address you need to encode the @ symbol i.e.

<imaps:inbound-endpoint user="no.way%40mulesource.com" password="xyz" host="imap.gmail.com" port="993"/>

It would be better if Mule did this transparently for this field

<imaps:inbound-endpoint user="no.way@mulesource.com" password="xyz" host="imap.gmail.com" port="993"/>