Added link to license page

Added link to http://www.gnu.org/copyleft/gpl.html - official license page of GNU General Public License.
Updated Polish translation.
Fixed some "errors" :)
Merge pull request #157 from ireun/patch-3

Updated Polish translation.
Compleated Polish translation :)
Merge pull request #158 from ireun/patch-4

Compleated Polish translation :)
Merge pull request #156 from benhc123/patch-5

Added link to license page
Fixed UI transfers list issue.
Added Yes/No dialog for shutdown action.
Added some security to avoid shutdown from external apps.
new exit icon and modified exit wifi sharing icon
added exit menu icon over state
New error message when fetch magnet times out.

Try again, not enough peers.
Merge pull request #159 from marcelinkaaa/exit-icon-changes

Exit icon changes
ignore intellij files
fix units on global transfer rate indicators
updates related to new exit icon
splits.abi enable.
Fixed ImageLoader to use new picasso request handlers API.
update polish translation

corrected spelling.