fix file size integer overflow in search results
fix file size integer overflow in search results

Closes #632.

losingle/seafile-client,haiwen/seafile-client,losingle/seafile-client,lucius-feng/seafile-client,losingle/seafile-client,haiwen/seafile-client,haiwen/seafile-client,losingle/seafile-client,lucius-feng/seafile-client,wgaalves/seafile-client,daodaoliang/seafile-client,wgaalves/seafile-client,lucius-feng/seafile-client,daodaoliang/seafile-client,daodaoliang/seafile-client,wgaalves/seafile-client,wgaalves/seafile-client,lucius-feng/seafile-client,haiwen/seafile-client,daodaoliang/seafile-client