Migrate plugins to lib directory

lib/plugins/common/kraken.js

@@ -0,0 +1,17 @@
+var BigNumber = require('bignumber.js')
+
+var TEN = new BigNumber(10)
+
+var UNIT_SCALES = {
+  BTC: 8,
+  ETH: 18
+}
+
+function unitScale (cryptoCoin) {
+  return UNIT_SCALES[cryptoCoin]
+}
+
+exports.toUnit = function toUnit (cryptoAtoms, cryptoCoin) {
+  var scale = TEN.pow(unitScale(cryptoCoin))
+  return cryptoAtoms.div(scale)
+}