Use git or http protocol to download dcmtk
Use git or http protocol to download dcmtk

DCMTK servers now support git protocol, use it by default.
Closes #33

Sardge/CTK,jcfr/CTK,finetjul/CTK,lassoan/CTK,CJGoch/CTK,espakm/CTK,AndreasFetzer/CTK,Heather/CTK,jcfr/CTK,Heather/CTK,rkhlebnikov/CTK,Heather/CTK,vovythevov/CTK,finetjul/CTK,CJGoch/CTK,laurennlam/CTK,pieper/CTK,mehrtash/CTK,SINTEFMedtek/CTK,ddao/CTK,Heather/CTK,commontk/CTK,commontk/CTK,jcfr/CTK,rkhlebnikov/CTK,SINTEFMedtek/CTK,fedorov/CTK,AndreasFetzer/CTK,vovythevov/CTK,AndreasFetzer/CTK,laurennlam/CTK,lassoan/CTK,Sardge/CTK,mehrtash/CTK,rkhlebnikov/CTK,commontk/CTK,mehrtash/CTK,laurennlam/CTK,CJGoch/CTK,mehrtash/CTK,ddao/CTK,danielknorr/CTK,espakm/CTK,msmolens/CTK,sankhesh/CTK,finetjul/CTK,sankhesh/CTK,lassoan/CTK,vovythevov/CTK,ddao/CTK,finetjul/CTK,espakm/CTK,msmolens/CTK,ddao/CTK,SINTEFMedtek/CTK,vovythevov/CTK,commontk/CTK,naucoin/CTK,fedorov/CTK,msmolens/CTK,sankhesh/CTK,fedorov/CTK,msmolens/CTK,naucoin/CTK,fedorov/CTK,CJGoch/CTK,laurennlam/CTK,jcfr/CTK,151706061/CTK,SINTEFMedtek/CTK,SINTEFMedtek/CTK,naucoin/CTK,Sardge/CTK,AndreasFetzer/CTK,Sardge/CTK,151706061/CTK,espakm/CTK,CJGoch/CTK,jcfr/CTK,lassoan/CTK,rkhlebnikov/CTK,naucoin/CTK,151706061/CTK,151706061/CTK,sankhesh/CTK,danielknorr/CTK,151706061/CTK,danielknorr/CTK,danielknorr/CTK,pieper/CTK,pieper/CTK,pieper/CTK