solves the windows issue (with symlinks) (#84)

* solved the windows issue with symlinks

Instead of symlinking to the hook in node-modules/pre-commit, this injects a new pre-commit hook (in .git/hooks) that takes care of launching the hook in node-modules/pre-commit. 
In addition it stashes the unstaged changes and applies them again after running the pre-commit hook, so that you only run your pre-commit scripts on the commit actual codebase.

* removed stashing

Stashing automatically is actually a bad idea, it's better to for the user to have control over doing it or not (manually then).

install.js

@@ -5,7 +5,7 @@
 //
 var fs = require('fs')
  , path = require('path')
- , spawn = require('cross-spawn')
+ , os = require('os')
  , hook = path.join(__dirname, 'hook')
  , root = path.resolve(__dirname, '..', '..')
  , exists = fs.existsSync || path.existsSync;
@@ -47,15 +47,28 @@ if (exists(precommit) && !fs.lstatSync(precommit).isSymbolicLink()) {
 try { fs.unlinkSync(precommit); }
 catch (e) {}
 
+// Create generic precommit hook that launches this modules hook (as well
+// as stashing - unstashing the unstaged changes)
+// TODO: we could keep launching the old pre-commit scripts
+var hookRelativeUnixPath = hook.replace(root, '.');
+if(os.platform() === 'win32') {
+ hookRelativeUnixPath = hookRelativeUnixPath.replace(/[\\\/]+/g, '/');
+}
+var precommitContent = '#!/bin/bash' + os.EOL
+ + hookRelativeUnixPath + os.EOL
+ + 'RESULT=$?' + os.EOL
+ + '[ $RESULT -ne 0 ] && exit 1' + os.EOL
+ + 'exit 0' + os.EOL;
+
 //
 // It could be that we do not have rights to this folder which could cause the
 // installation of this module to completely fail. We should just output the
 // error instead destroying the whole npm install process.
 //
-try { fs.symlinkSync(path.relative(hooks, hook), precommit, 'file'); }
+try { fs.writeFileSync(precommit, precommitContent); }
 catch (e) {
  console.error('pre-commit:');
- console.error('pre-commit: Failed to symlink the hook file in your .git/hooks folder because:');
+ console.error('pre-commit: Failed to create the hook file in your .git/hooks folder because:');
  console.error('pre-commit: '+ e.message);
  console.error('pre-commit: The hook was not installed.');
  console.error('pre-commit:');