Review naming

[ducthotran2010]

ronin-dpos-contracts/contracts/ronin/Maintenance.sol

Line 142 in 2ef51c7

function maintaining(address _consensusAddr, uint256 _block) public view returns (bool) {

    Note: same for `bulkMaintaining`

1. Naming: confusing names

2. As stated in the comment of scheduled, the checking must be done in range of blocks, not just by a timestamp indicated by a single block.

Originally posted by @nxqbao in #22 (comment)

[nxqbao]

I think should add is/bulkIs prefix to view methods that returns bool/bool[] for clarity.
Adding them also partially solves #69.

[ducthotran2010]

The pattern bulk + function name should work fine for the mutable functions, but for the view functions, we can workaround by renaming them, e.g:

• jailed: getJailedStatus and getJailedStatuses
• stakingAmountOf: getStakingAmount and getStakingAmounts