Added simple python install check

Now tries to run the "python" command first, if it fails it tries default install path "C:\python27\python.exe".
Returns "Check Python install" if those 2 fail.

Extract keys.bat

@@ -1,2 +1,11 @@
+@echo off
 python walletaid.py
+IF ERRORLEVEL 1 (
+	CLS
+	"C:\python27\python.ee" walletaid.py
+)
+if ERRORLEVEL 1 (
+	CLS
+	ECHO Check Python install
+)
 @pause