conv.contexts.get is case sensitive

[tomhalley]

As the title suggests, a value of "my_context" passed to conv.contexts.get will match a context defined in DialogFlow as "MY_CONTEXT", but if I pass it "MY_CONTEXT", the getter returns undefined. DialogFlow context names aren't case sensitive, so this creates some confusion

[Fleker]

In JSON and Javascript, keys and variables are case-sensitive.