Change seed file with a bip39 mnemonic (#207)

* Change seed file with a bip39 mnemonic

* Create helper for bip39 mnemonic

* Prod mode on lamassu-update-to-mnemonic script

* Fix standard styling issues

bin/lamassu-update-to-mnemonic

@@ -0,0 +1,30 @@
+#!/usr/bin/env node
+
+'use strict'
+
+const fs = require('fs')
+const path = require('path')
+const os = require('os')
+const mnemonicHelpers = require('../lib/mnemonic-helpers')
+const options = require('../lib/options-loader')()
+
+if (!options.opts.mnemonicPath && options.opts.seedPath) {
+  const seed = fs.readFileSync(options.opts.seedPath, 'utf8').trim()
+  const mnemonic = mnemonicHelpers.fromSeed(seed)
+
+  if (process.argv[2] === '--prod') {
+    options.opts.mnemonicPath = path.resolve('etc', 'lamassu', 'mnemonics', 'mnemonic.txt')
+  } else {
+    options.opts.mnemonicPath = path.resolve(os.homedir(), '.lamassu', 'mnemonics', 'mnemonic.txt')
+  }
+
+  if (!fs.existsSync(path.dirname(options.opts.mnemonicPath))) {
+    fs.mkdirSync(path.dirname(options.opts.mnemonicPath))
+  }
+
+  if (!fs.existsSync(options.opts.mnemonicPath)) {
+    fs.writeFileSync(options.opts.mnemonicPath, mnemonic, 'utf8')
+  }
+
+  fs.writeFileSync(options.path, JSON.stringify(options.opts, null, '\t'), 'utf8')
+}