Adding starter code and solution for p4runtime exercise (#81)

Summary of changes:
- Adding the p4runtime starter code and solution.
- Adding NO_P4, BMV2_SWITCH_EXE and P4C_ARGS to utils/Makefile
- Updated p4runtime/Makefile to use variables
- Adding conversion functions for match and action param values
- Separating P4Info and P4Runtime libraries
- Updating global README and adding p4runtime/README.md
- Disabling screen saver on VM GUI
- Adding desktop icons for Terminal, Wireshare and Sublime Text
- Updating topo.pdf -> png for Markdown viewing in basic_tunnel and
  p4runtime READMEs

P4D2_2017_Fall/vm/root-bootstrap.sh

@@ -76,3 +76,6 @@ ln -s p4-logo.png lubuntu-default-wallpaper.png
 rm /home/vagrant/p4-logo.png
 cd /home/vagrant
 sed -i s@#background=@background=/usr/share/lubuntu/wallpapers/1604-lubuntu-default-wallpaper.png@ /etc/lightdm/lightdm-gtk-greeter.conf
+
+# Disable screensaver
+apt-get -y remove light-locker

P4D2_2017_Fall/vm/user-bootstrap.sh

@@ -131,3 +131,39 @@ cd /home/vagrant
 sudo mv .vim /home/p4/.vim
 sudo chown -R p4:p4 /home/p4/.vim
 
+# Adding Desktop icons
+DESKTOP=/home/${USER}/Desktop
+mkdir -p ${DESKTOP}
+
+cat > ${DESKTOP}/Terminal << EOF
+[Desktop Entry]
+Encoding=UTF-8
+Type=Application
+Name=Terminal
+Name[en_US]=Terminal
+Icon=konsole
+Exec=/usr/bin/x-terminal-emulator
+Comment[en_US]=
+EOF
+
+cat > ${DESKTOP}/Wireshark << EOF
+[Desktop Entry]
+Encoding=UTF-8
+Type=Application
+Name=Wireshark
+Name[en_US]=Wireshark
+Icon=wireshark
+Exec=/usr/bin/wireshark
+Comment[en_US]=
+EOF
+
+cat > ${DESKTOP}/Sublime\ Text << EOF
+[Desktop Entry]
+Encoding=UTF-8
+Type=Application
+Name=Sublime Text
+Name[en_US]=Sublime Text
+Icon=sublime-text
+Exec=/opt/sublime_text/sublime_text
+Comment[en_US]=
+EOF