Renamed Exempt Delegation to Validator Bond

[sampocs]

This is the same as #60, which was already approved (it was just accidentally merged to the wrong base branch)

• Renamed ExemptDelegation to ValidatorBond
• Renamed ExemptionFactor to ValidatorBondFactor
• Replaced all occurrences of "exempt" terminology

[sampocs]

@faddat - this is the same as #60 just pointed to master instead!

[faddat]

You got it sir