Adds a standard DONT_CARE pin name that allows specifying that any pin will
work in a pin map.  This is currently used in the NRF51822 serial API to allow
specifying any pins as a UART.
Revert "Adds a standard DONT_CARE pin name that allows specifying that any pin will..."

This reverts commit c804dc8013bb067d0281f082ed28c5e07aca0541.
Disables checking UART pins checking on nRF51822.
[NUCLEOs] Set heap size to 0x400
Merge pull request #447 from webbbn/nrf51822_uart_any_pin

Adds standard DONT_CARE pin name for specifying that any pin will work
Merge pull request #449 from bcostm/master

[NUCLEOs] Set heap size to 0x400
Change pins for RBL nRF51822 board.
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