Adv data retrieve

[polldo]

based on https://github.com/arduino-libraries/ArduinoBLE/pull/150/files and https://github.com/arduino-libraries/ArduinoBLE/pull/162/files

• enables retrieval of remote advertising data
• enables retrieval of remote manufacturer data

It needs to be tested
@manchoz

[rhempel]

+1 for this - I have a project where the advertising data contains button state, and I only want to scan for and connect to devices with a specific UUID where the button is pressed.

Great little library otherwise :-)

[manchoz]

@polldo LGTM 👍

[manchoz]

@facchinm please merge this one, too.