Code refactoring & truffle support

[AntMarras]

@simondlr
This PR:

• Add gitignore
• add backbone of truffle for future testing
• Refactor the CurationMarkets.sol by splitting it in different files to help future development

Please note that I had to introduce two changes in order to make the contracts compile & deploy:

1. By compiling I faced the error
   Internal compiler error: Accessors for mapping with dynamically-sized keys not yet implemented.
   this is due to the fact that mapping doesn't support accessors where string is a key. So I had to creat a getter for totalBondsPerCuratorPerSubtopic function getTotalBondsPerCuratorPerSubtopic(address _curator, string _subtopic) returns(uint256); and remove the public accessor from it and from the bonds mapping. (more info: Raise useful error message when using a dynamic type as a key in a mapping ethereum/solidity#633)

2. in ContinuousToken constructor the line // updateCostOfToken(0); make run of gas the contract creation, so I changed it in
   costPerToken = 2 * baseCost;
   it cames from the formula:

costOfToken = (BaseCost + BaseCost (1.000001618^AvailableSupply)+BaseCost*AvailableSupply/1000)

with an initial AvailableSupply = 0

These are fixes just to make it compile and run. All the code still needs to be polish.