Merge pull request #451 from Cheong2K/master

Change pins for RBL nRF51822 board.
use target group LPC11UXX
Merge pull request #453 from xiongyihui/usb

[USBDevice] use target group LPC11UXX instead of LPC11U24 or LPC11U35_501
[NUCLEO_L053R8] Fix bug and improvement of AnalogIn
Merge pull request #455 from bcostm/master

[NUCLEO_L053R8] Fix bug and improvement of AnalogIn