Update file to point at master branch (#501)

The file is pointing at the development branch instead of master.

account_setup.sh

@@ -4,7 +4,7 @@ echo "Installing depdendencies..." &&
 pip install --force-reinstall --upgrade --user pyyaml==3.12 azure==3.0.0 azure-cli-core==2.0.30 msrestazure==0.4.25 > /dev/null 2>&1 &&
 echo "Finished installing depdencies." &&
 echo "Getting account setup script..." &&
-wget -q https://raw.githubusercontent.com/Azure/aztk/feature/getting_started_scripts/account_setup.py -O account_setup.py &&
+wget -q https://raw.githubusercontent.com/Azure/aztk/master/account_setup.py -O account_setup.py &&
 chmod 755 account_setup.py &&
 echo "Finished getting account setup script." &&
 echo "Running account setup script..." &&