Improved messaging of variables in run_server.sh
Improved messaging of variables in run_server.sh

This change improves the messaging for each variable in
that the run_server.sh script expects. Running ther script
with any value missing will yield a usage message.

ditadewindita/CodeUSummer2017,oldmud0/codeu17-group18,lysanderp41/CodeUSummer2017,hv14/CodeU-Summer-2017,goldfeyesh/codeu_project_2017,mganesh6/codeu_project_2017,turtlefarmer/codeu_project_2017,lee-tammy/CodeU-Summer-2017,JacobWarner/codeu_project_2017,lianasyrkett/CodeU-Summer-2017,taylordarnell/CodeU-Summer-2017,nikkibisarya/CodeU-Summer-2017,vgomezASC/CodeU-Summer-2017,lysanderp41/CodeUSummer2017,justarvin/codeusummer2017,petosa/codeu_project_2017,crepric/codeu_mirrored_test_1,jedouard98/codeu_summer_2017,sntnmjones/codeu_project_2017,nerissalin/codeu_project_2017,someoneemily/CodeU-Summer-2017,HuyLafa/codeu_project_2017,lianasyrkett/CodeU-Summer-2017,ymittal/codeu_project_2017,nerissalin/codeu_project_2017,vgomezASC/CodeU-Summer-2017,HuyLafa/codeu_project_2017,Priya411/CodeUGroup3,cqdinh/codeu_project_2017,JacobWarner/codeu_project_2017,laurho/codeu_project_2017,laurho/codeu_project_2017,Priya411/CodeUGroup3,justarvin/codeusummer2017,laurho/codeu_project_2017,preska/codeu_project_2017,cgon50/CodeU-Summer-2017,mganesh6/codeu_project_2017,lee-tammy/CodeU-Summer-2017,goldfeyesh/codeu_project_2017,sntnmjones/codeu_project_2017,preska/codeu_project_2017,EVelez79/CodeU-ProjectGroup6,EVelez79/CodeU-ProjectGroup6,petosa/codeu_project_2017,laurho/codeu_project_2017,GrayTurtle/codeu_project_2017,crepric/codeu_mirrored_test_1,someoneemily/CodeU-Summer-2017,GrayTurtle/codeu_project_2017,nikkibisarya/CodeU-Summer-2017,cqdinh/codeu_project_2017,taylordarnell/CodeU-Summer-2017,google/codeu_project_2017,laurho/codeu_project_2017,oldmud0/codeu17-group18,Pandarati/CodeU-Summer-2017,petosa/codeu_project_2017,laurho/codeu_project_2017,cgon50/CodeU-Summer-2017,Pandarati/CodeU-Summer-2017,ditadewindita/CodeUSummer2017,petosa/codeu_project_2017,petosa/codeu_project_2017,HuyLafa/codeu_project_2017,hv14/CodeU-Summer-2017,jedouard98/codeu_summer_2017,ymittal/codeu_project_2017,google/codeu_project_2017,HuyLafa/codeu_project_2017,turtlefarmer/codeu_project_2017