bci: Remove non-significant advertising data part from in-air packet

Generic Access Profile specification section 11, Core 4.1 page 2023:
"Only the significant part of the Advertising or Scan Response data
needs to be sent over the air."
radio: Posfix radio_handler type with cb
ll: Add ll_set_advertising_params() API
bci: Pack advertise parameters into a struct
bci: Add bci_get_advertising_params() API
bci: Add bci_set_advertising_params() API
bci: Move advertising data maximum length definition to bci.h
bdaddr: Move bdaddr_t definition to bdaddr.h
stack: Split adv_type_t into bci_adv_t and ll_pdu_t types

Now the LL layer only knows about advertising PDUs and the BCI layer is
responsible to make the translation between the types.
stack: Remove ble-common.h header
assert: Add header containing a static assert macro
bci: Prefix ENABLE and DISABLE definitions with BCI
bci: Assert statically BCI/LL common symbols
blessed: Rename project from blestack to blessed
blessed: Move public headers to include/blessed
nrf51822: Remove hardcoded path to NRF51 SDK

Now, the user needs to provides NRF51_SDK_PATH to the build system. He
can pass it via make command line:

	$ make NRF51_SDK_PATH=/path/to/sdk

Or put it inside Makefile.config (recommended way):

	$ echo "NRF51_SDK_PATH=/path/to/sdk" >> Makefile.config
	$ make

NRF51_SDK_PATH must point to the directory that contains `nrf51822`
path.

Currently, blessed only supports the SDK version 4.4.x.
nrf51822: Add support for other Nordic boards

Until now, only old versions of PCA10001 evaluation board were
supported. This patch allows the user to reassign those variables
in order to compile blessed to those boards.

This patch wasn't tested with other nRF51822 boards.
nrf51822: Add README
examples: Update README
blessed: Update README