[EPIC] Allow more customizable light client parameters

[srdtrk]

I've published this repo with the assumption of default client parameters (on the side of the operator, the contract shouldn't need any changes). These default parameters are:

• Trust Level: 1/3
• Trusting Period: 2 weeks
• Unbonding Period: 2 weeks

Therefore, we should allow the user to set these parameters on genesis. Then the operator can query them while running.

• Allow customization of trust_level #64
• Allow customization of trusting_period #70
• Allow customization of unbonding_period #68