fix(bitcoin-unit): allow NaN values

New version of bitcoin-convert supports conversion of NaN values.

Author: richardschneider

package.json

@@ -22,7 +22,7 @@
     "autolinker": "^0.22.0",
     "backbone": ">=1.2.1",
     "backbone.localstorage": "^1.1.16",
-    "bitcoin-convert": "^1.0.2",
+    "bitcoin-convert": "^1.0.4",
     "chosen": "0.0.2",
     "cropit": "0.5.1",
     "ini": "^1.3.4",