Fixed throw on DebuggerAgent.resume()

Addressed issues/277. The adjustment to args.maxStringLength in
lib/DebuggerClient.js:90 (a fix for issues/29) performed only if args
is defined.
Fix Date display format. Issue #281

Removed 'Date: ' prefix.
Added Inspector object type 'date'
Checked test 'appends formatted date to Date description...'
Fixed misspelled word "Visit" in docs

docs/embedding.md had a misspelled word