Remove setup.js and decouple install.js and uninstall.js

Make uninstall.js independent of 3rd party modules. There is an npm v3
bug that (sometimes) uninstalls 3rd party modules before running your
uninstall script which may rely on those modules.

Refs npm/npm#11894

Author: Alexander Lisianoi

install.js

@@ -1,15 +1,42 @@
+var fs = require('fs')
+var path = require('path')
 var chalk = require('chalk')
-var setup = require('./setup')
-
-if (setup.selfmadeHook) {
-  console.log('Found an existing commitplease hook, removing to update it')
-  setup.destroy()
-} else if (setup.hookExists) {
-  console.log(chalk.red('Detected an existing git commit-msg hook'))
-  console.log('')
+
+var options = require('./index.js').getOptions()
+
+if (options && options.nohook) {
+  console.log('commitplease: package.json or .npmrc set to skip hook')
+  process.exit(0)
+}
+
+var git = path.resolve(process.cwd(), '..', '..', '.git')
+var hooks = path.join(git, 'hooks')
+
+if (!fs.existsSync(git) || !fs.existsSync(hooks)) {
+  fs.mkdirSync(git)
+  fs.mkdirSync(hooks)
+}
+
+var dstHook = path.join(hooks, 'commit-msg')
+var srcHook = path.relative(hooks, 'commit-msg-hook.js')
+
+if (fs.existsSync(dstHook)) {
+  console.log(chalk.red('A commit-msg hook already exists'))
   console.log(chalk.red('Remove it and install this package again to install commitplease properly'))
   process.exit(0)
 }
 
-setup.create()
-console.log('Installed ' + setup.hook)
+try {
+  fs.writeFileSync(dstHook, fs.readFileSync(srcHook))
+  fs.chmodSync(dstHook, '755')
+} catch (e) {
+  if (/EPERM/.test(e.message)) {
+    console.error(
+      chalk.red(
+        'Failed to write commit-msg hook. ' +
+        'Make sure you have the necessary permissions.'
+      )
+    )
+  }
+  throw e
+}

setup.js

@@ -1,8 +1,16 @@
-var setup = require('./setup')
+var fs = require('fs')
+var path = require('path')
 
-if (setup.selfmadeHook) {
-  console.log('Found a hook installed by commitplease, removing')
-  setup.destroy()
-} else {
-  console.log("Didn't find a commit-msg hook installed by this module, doing nothing")
+var hooks = path.join(process.cwd(), '..', '..', '.git', 'hooks')
+
+var dstHook = path.join(hooks, 'commit-msg')
+var srcHook = path.relative(hooks, 'commit-msg-hook.js')
+
+if (fs.existsSync(dstHook) && fs.existsSync(srcHook)) {
+  var githook = fs.readFileSync(dstHook, 'utf-8')
+  var comhook = fs.readFileSync(srcHook, 'utf-8')
+  if (githook.toString() === comhook.toString()) {
+    console.log('Removing the hook installed by commitplease')
+    fs.unlinkSync(dstHook)
+  }
 }