Add logkv command for logging key-value pairs

- logkv : <context> <level> <msgID> <key>=<value> <...> <messsage>

e.g.)
- PmLogCtl logkv test info my_id key1=\"value\" "key2=\"foo bar\""
key3=true key4=false key5=\"true\" key6=\"false\" key7=100
key8=3.141592 my_message
- PmLogCtl logkv test info my_id my_message

[GF-3821] Add new log command to log using the new key-value pair API

Open-webOS-DCO-1.0-Signed-off-by: Hongjeon Ha <hj.ha@lge.com>

Change-Id: I3b9546abb232efcb1b0816b5095e8ecb65a5c02c
Reviewed-on: https://g2g.palm.com/1959
Reviewed-by: Build Verification
Reviewed-by: Hongjeon Ha <hj.ha@lge.com>
Tested-by: Hongjeon Ha <hj.ha@lge.com>
Reviewed-by: Keith Derrick <keith.derrick@lge.com>
Reviewed-by: Gayathri Srinivasan <gayathri.srinivasan@lge.com>