Various fixes and formatting chores (#885)

* fix: clean up solium linting errors

* fix: make various contracts natspec compliant

* fix: this.balance deprecated; convert to address(this).balance

* fix: contract.call deprecated and switch to gasleft()

* fix: ignore empty block rule project-wide

* fix: add ignore cases for the rest of the linting warnings

contracts/crowdsale/Crowdsale.sol

@@ -82,7 +82,12 @@ contract Crowdsale {
     weiRaised = weiRaised.add(weiAmount);
 
     _processPurchase(_beneficiary, tokens);
-    emit TokenPurchase(msg.sender, _beneficiary, weiAmount, tokens);
+    emit TokenPurchase(
+      msg.sender,
+      _beneficiary,
+      weiAmount,
+      tokens
+    );
 
     _updatePurchasingState(_beneficiary, weiAmount);
 

contracts/crowdsale/distribution/utils/RefundVault.sol

@@ -44,7 +44,7 @@ contract RefundVault is Ownable {
     require(state == State.Active);
     state = State.Closed;
     emit Closed();
-    wallet.transfer(this.balance);
+    wallet.transfer(address(this).balance);
   }
 
   function enableRefunds() onlyOwner public {

contracts/crowdsale/price/IncreasingPriceCrowdsale.sol

@@ -34,6 +34,7 @@ contract IncreasingPriceCrowdsale is TimedCrowdsale {
    * @return The number of tokens a buyer gets per wei at a given time
    */
   function getCurrentRate() public view returns (uint256) {
+    // solium-disable-next-line security/no-block-members
     uint256 elapsedTime = block.timestamp.sub(openingTime);
     uint256 timeRange = closingTime.sub(openingTime);
     uint256 rateRange = initialRate.sub(finalRate);

contracts/crowdsale/validation/TimedCrowdsale.sol

@@ -18,6 +18,7 @@ contract TimedCrowdsale is Crowdsale {
    * @dev Reverts if not in crowdsale time range.
    */
   modifier onlyWhileOpen {
+    // solium-disable-next-line security/no-block-members
     require(block.timestamp >= openingTime && block.timestamp <= closingTime);
     _;
   }
@@ -28,6 +29,7 @@ contract TimedCrowdsale is Crowdsale {
    * @param _closingTime Crowdsale closing time
    */
   function TimedCrowdsale(uint256 _openingTime, uint256 _closingTime) public {
+    // solium-disable-next-line security/no-block-members
     require(_openingTime >= block.timestamp);
     require(_closingTime >= _openingTime);
 
@@ -40,6 +42,7 @@ contract TimedCrowdsale is Crowdsale {
    * @return Whether crowdsale period has elapsed
    */
   function hasClosed() public view returns (bool) {
+    // solium-disable-next-line security/no-block-members
     return block.timestamp > closingTime;
   }