Removed get part in return methods.

In case method name is getValue(), it was renamed to value().

Change-Id: I914e16bd0b630c0810932c52af14f091cc35bd8f
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>
Implemented the characteristic error handling.

In case of enabling notifications and writing values to the LE device, some errors can occur and which are reported now.

Change-Id: I02c6deab925d06916c5b56705c9423386400f713
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>
Implemented Bluetooth Low Energy: autotests

Autotests added for new Bluetooth LE classes.

Change-Id: I31742786104df2aa9ec68ec9a82606f1e227c198
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>