Don't add custom parameters if array size is exceeded
Don't add custom parameters if array size is exceeded

array containing custom parameters is initialised at class
initialization time with a fixed value. When we later try to add more
parameters than the array allows we will now discard the offending
parameters and make a debug logging so the developer knows what's going
on.

Might be further improved as per this answer on StackOverflow:
http://stackoverflow.com/a/12271501
This would allow the array size to be specified at initialisation time,
and would give flexibility to the developer to decide how big the array
should be.

closes tzapu/WiFiManager#285

tablatronix/WiFiManager,tablatronix/WiFiManager,tzapu/WiFiManager,tzapu/WiFiManager,tablatronix/WiFiManager,tablatronix/WiFiManager,tzapu/WiFiManager,tablatronix/WiFiManager,tzapu/WiFiManager,tzapu/WiFiManager