VM Updates (#83)

- Minor fixes to p4runtime exercise and README
- Adding p4runtime/solution
- Adding p4runtime/topology.json
- Updating .gitignore to include solution directory and topology.json
- Fixing root-bootstrap to exit on errors
- Updating VM name in Vagrantfile
- Setting up VM to automatically log 'p4' user in on startup

.gitignore

@@ -8,11 +8,13 @@
 # Compiled JSON
 *.json
 !*p4app.json
+!topology.json
 
 *.pcap
 
 # Extracted solutions
 solution*/
+!solution/
 
 # Build folders
 build*/