cpu: added support for the i.MX6 (SWP)
board: initial commit for the RIoTboard (SWP)

    Adds basic (the most "basic" you can think of) support of the RIoTboard to RIoT-OS.
    In this case "basic" means: The UART(I/O) is working, it's possible to include the automatically generated sources from the IOMUX-Config-tool. Timers are implemented. Threading isn't.
    Currently, there is a while(1)-loop in board init to prevent weird stuff from happening when progressing to kernel_init.
    This port is based entirely on the official platform-SDK from freescale.
    The overall quality is not what it should be.

    We intend to continue working on this stuff till it's working properly and the code is cleaned up.