Add documentation for each moonCatUtils function

The library file moonCatUtils.js exports several helper functions that can make interacting with MoonCat-related smart contracts easier. Each of those should have documentation created for them, for developers to more easily use them.

• Create a new section (H1) in /README.md entitled "MoonCat Utils library"
• Under that section, create a sub-section for each export from the moonCatUtils.js file. For each export, give a brief summary of the function, and an example javascript snippet calling that function.
• Add Doxygen/Javadoc/JSDoc-style comment blocks before each function in the moonCatUtils.js file, documenting their purpose and usage instructions.