GetOrCreateRuleSessionFromConfig is hardcoding context

[magallardo]

Current behavior (how does the issue manifest):
When rules are created from config file, the context is hardcoded
Expected behavior:
The context should be set from the value provided in config file. If value is not provided, the . it should be defaulted to the hardcoded value
Minimal steps to reproduce the problem (not required if feature enhancement):
Just creating a rule with a config file, all rules will have the same value
Please tell us about your environment (Operating system, docker version, browser & web ui version, etc):
MacOS
Flogo Rules version (CLI & contrib/lib. If unknown, leave empty or state unknown): 0.X.X
0.5.8
Additional information you deem important (e.g. issue happens only occasionally):