bug fix using "pio" instead of "platformio" to know the PlatformIO version. Some Linux distro and OSX versions are not working well, when "pio" is use

Author: gepd

beginning/pio_install.py

@@ -256,7 +256,7 @@ def check_pio():
 
     Check if platformIO is already installed in the machine
     """
-    cmd = ['pio', '--version']
+    cmd = ['platformio', '--version']
     out = run_command(cmd)
 
     status = out[0]