Implemented rpc server method GetRawTransaction (#135)

* Added utility function GetVarSize

* 1) Added Size method: this implied that Fixed8 implements now the serializable interface. 2) Added few arithmetic operation (Add, Sub, div): this will be used to calculated networkfeeand feePerByte. Changed return value of the Value() method to int instead of int64. Modified fixed8_test accordingly.

* Implemented Size or MarshalJSON method.
- Structs accepting the Size method implement the serializable interface.
- Structs accepting the MarshalJSON method implements the customized json marshaller interface.

* Added fee calculation

* Implemented rcp server method GetRawTransaction

* Updated Tests

* Fixed:
1) NewFixed8 will accept as input int64
2) race condition affecting configDeafault, blockchainDefault

* Simplified Size calculation

* 1) Removed global variable blockchainDefault, configDefault
2) Extended Blockchainer interface to include the methods: References, FeePerByte, SystemFee, NetworkFee
3) Deleted fee_test.go, fee.go. Moved corresponding methods to blockchain_test.go and blockchain.go respectively
4) Amended tx_raw_output.go

* Simplified GetVarSize Method

* Replaced ValueAtAndType with ValueWithType

* Cosmetic changes + Added test case getrawtransaction_7

* Clean up Print statement

* Filled up keys

* Aligned verbose logic with the C#-neo implementation

* Implemented @Kim requests
Refactor server_test.go

* Small fixes

* Fixed verbose logic
Added more tests
Cosmetic changes

* Replaced assert.NoError with require.NoError

* Fixed tests by adding context.Background() as argument

* Fixed tests

pkg/core/util.go

@@ -170,7 +170,7 @@ func calculateUtilityAmount() util.Fixed8 {
 	for i := 0; i < len(genAmount); i++ {
 		sum += genAmount[i]
 	}
-	return util.NewFixed8(sum * decrementInterval)
+	return util.NewFixed8(int64(sum * decrementInterval))
 }
 
 // headerSliceReverse reverses the given slice of *Header.