Added timeout to incomingCallNumber for avoiding spurious RI commutations

[thomasricci]

Added timeout (500 ms) to incomingCallNumber method in order to avoid blocking behaviour due to spurious FONA RI pin commutations.
Added rejectIncomingCalls and acceptIncomingCalls methods to enable or disable "busy" mode.
Added HardwareSerial implementation for supporting Intel Galileo board

[dsteinel]

thanks alot for this fix! Helped me alot. But the time it takes to make a call raised from 10000ms to 15000ms. But it is still very helpful!
Thanks for that!

[toddtreece]

@thomasricci sorry for the delay in looking at this change. could you possibly merge in the latest upstream master? that would really help expedite the review process once limor gets a chance to look at the open pull requests.

thanks for the help!

[ladyada]

shoot its been such a while since i checked out this pull req i cant merge it. but its just a line right @thomasricci ? can you tell me where to place the delay and ill just do it manually :)

[UdFrederic]

Hello! I have recently bought a FONA shild V2 with SIM R14.18 and I am encountering blockings when using the function "callerIdNotification" with last code (version of Jan. 21st, 2016).
Could you please check or give any advice? Thank you very much!
Regards, UdFrederic