Add exec (#10)

* Add exec

* Fix linux tests

* unnecessary dependency

* Dont prefix ExecOptions with I

* Consistency nits

* Respond to feedback

* Add toolrunner explanatory quote

* Format

packages/exec/__tests__/scripts/wait-for-file.js

@@ -0,0 +1,35 @@
+var fs = require('fs');
+
+// get the command line args that use the format someArg=someValue
+var args = {};
+process.argv.forEach(function (arg) {
+    var match = arg.match(/^(.+)=(.*)$/);
+    if (match) {
+        args[match[1]] = match[2];
+    }
+});
+
+var state = {
+    file: args.file
+};
+
+if (!state.file) {
+    throw new Error('file is not specified');
+}
+
+state.checkFile = function (s) {
+    try {
+        fs.statSync(s.file);
+    }
+    catch (err) {
+        if (err.code == 'ENOENT') {
+            return;
+        }
+
+        throw err;
+    }
+
+    setTimeout(s.checkFile, 100, s);
+};
+
+state.checkFile(state);