Added support for es_ES locale (#197)

* Added support for es_ES 

Creation of es_ES locale in locales folder

* Adding locale option to config.h

Adding option to activate es_ES locale to config.h

Author: serghidalg

platformio/include/config.h

@@ -72,6 +72,7 @@
 //   Italiano (Italia)               it_IT
 //   Dutch (Belgium)                 nl_BE
 //   Portuguese (Brazil)             pt_BR
+//   Spanish (Spain)                 es_ES
 #define LOCALE en_US
 
 // UNITS