issue0009: quick download

if file & md5 exist, verify md5 first

Change-Id: I20ffacf155274406d586fe15bf318fb4d270a0b9
issue0010: Wait signal

Change-Id: Ib71b04dfbfb78396b29759b905fc6f30b0a18bb1
Merge branch 'iceyer/issue0009-quick-download' into develop
Merge branch 'iceyer/issue0010-Wait-signal' into develop