[SHELL] Fixed switching between BT shell and JIMTCL shell support.
[SHELL] date - Added a date command to print the current system time.
[TIMERS] System Tim API should cause an atomic operation when reading from the system timer.
[ARCH] ARM - types - Corrected BT_s16 type.
[TIME] Added new time sub-system.
[TIME] bt_time_to_tm() api now accepts bt_tm struct.