support chinese character for ota package's path

It had been tested work well for both english characters 
and chinese english misc characters.
Because utf-8 is supported in recovery mode, so
if we stored message by utf-8 encoding, we can
handle non-ascii character for ota packages's path.

Change-Id: I19555dc75640bbfd481f23009bff511c07ae0bdb
Signed-off-by: aquanox <aquanox@163.com>