[sailfish-browser] Improve size handling for launcher icons

Separate acceptable and accepted touch icons and set iconType
only if it is big enough.

This fixes launcher icons for sites like:
m.engadget.com, m.iltalehti.fi, m.spiegel.de
Merge pull request #158 from rainemak/launcherIconFix

[sailfish-browser] Improve size handling for launcher icons