Support database search for HAL system-info

Support database search for HAL system-info

In addition to platform system-info database(/etc/system_info_db),
system-info of HAL(/hal/system_info_db) can be searched for a requested
key.
 If a key exists only in one database, use it.
 If a key exists in both of the databases,
   - if value of key is type of bool, the two value are ANDed.
   - if value of key is type of other than bool, the value of HAL is
     used.

Change-Id: If36a4b7a4143107ec550bb1311dafb470f492167
Signed-off-by: Youngjae Cho <y0.cho@samsung.com>