improvement(HomeProjectDropdown.js): REfactored code to implement feedback
improvement(HomeProjectDropdown.js): REfactored code to implement feedback

Used browserHistory to push the active project id to the URL to get the activeproject.id to connect
to the react-select onchange prop

#650

conveyal/datatools-manager,conveyal/datatools-manager,conveyal/datatools-manager,conveyal/datatools-manager