fix: limit new comments to 3000 characters
fix: limit new comments to 3000 characters

see issue #12
This does not resolve the issue but is the first step
towards enforcing an upper limit on comment text

tstillwell2k17/GAE-BLOGAPP-MULTI_USER-DEMO,tstillwell2k17/GAE-BLOGAPP-MULTI_USER-DEMO,tstillwell2k17/GAE-BLOGAPP-MULTI_USER-DEMO