Moves test/misc.js tests to appropriate location
Removes use of convert module
Updates network.js constant names
Adds Buffers as input parameters
Renames network parameter to netstr

This should make the intent clearer.
This commit also catches the `null` case for the seed parameter.
HDWallet now uses Buffers internally
Removes format dependency
Moves derivation math out into the open
Merge pull request #133 from dcousens/network

Updates network.js constant names
Merge pull request #134 from dcousens/hdwalletbuf

HDWallet now uses Buffers internally
Merge pull request #132 from dcousens/remmisc

Removes test/misc.js and moves tests to appropriate location
Changes netstr to networkString