Initial commit of a more flexible mailtransport, including support for Akonadi resource-based transports.

Changes include:

• separate config widgets for each transport type (smtp, sendmail, akonadi)
• a nice KAssistantDialog for adding transports
• support for renaming transports in the management widget

A lot is still TODO, and this will eventually need an API review.

svn path=/branches/kdepim/soc/kdepimlibs/; revision=977460