CurieBLE: descriptor.read() does not block

[sandeepmistry]

Similar to #383 but for descriptor.

I would like to remove the delay(1000); statements from the peripheral_explorer example. So, expect descriptor.read() to behave like characteristic.read() and block.

[SidLeung]

Tracked by Jira 890.

[russmcinnis]

We have system tested, but not unit tested yet.

[russmcinnis]

@SidLeung I was expecting the delay(1000) to be removed from peripheral_explorer.ino so this needs an update.
// read the descriptor value
descriptor.read();
delay(1000);

[sandeepmistry]

This looks good now with the 2.0.2 RC JSON @SidLeung provided me. Closing.

I'll open a small to remove the delay(1000);'s in the peripheral_explorer.ino as @russmcinnis mentioned above.

Here's the result from running again bleno's test.js on a Raspberry Pi (I had to mod the sketch to scan with duplicates as mentioned in #370):

Found B8:27:EB:1C:39:03 '' ffffffff-ffff-ffff-ffff-fffffffffff0
Found B8:27:EB:1C:39:03 'test' ffffffff-ffff-ffff-ffff-fffffffffff0
Connecting ...
Connected
Discovering attributes ...
Attributes discovered

Device name: 
Service 1800
Service 1801
Service ffffffff-ffff-ffff-ffff-fffffffffff0
	Characteristic ffffffff-ffff-ffff-ffff-fffffffffff1, properties 0x2, value 0x76616C7565
		Descriptor 2901, value 0x75736572206465736372697074696F6E
	Characteristic ffffffff-ffff-ffff-ffff-fffffffffff2, properties 0x2, value 0x64796E616D69632076616C7565
	Characteristic ffffffff-ffff-ffff-ffff-fffffffffff3, properties 0x2, value 0x000102030405060708090A0B0C0D0E0F10111213
	Characteristic ffffffff-ffff-ffff-ffff-fffffffffff4, properties 0x12
	Characteristic ffffffff-ffff-ffff-ffff-fffffffffff5, properties 0x16
	Characteristic ffffffff-ffff-ffff-ffff-fffffffffff6, properties 0x32

Disconnecting ...
Disconnected