Add process.startTime

doc/api.txt

@@ -112,6 +112,9 @@ The PID of the process.
 +process.platform+ ::
 What platform you're running on. +"linux2"+, +"darwin"+, etc.
 
++process.startTime+ ::
+When the process started.
+
 +process.memoryUsage()+ ::
 Returns the memory usage of the Node process. It looks like this
 +

src/node.js

@@ -1,4 +1,5 @@
 (function (process) {
+process.startTime = new Date();
 
 process.global.process = process;
 process.global.global = process.global;