io: wrap data-pointer sending into additional elliptics::data_pointer(), since ->send_data() requires rvalue which is can modify
tests: stop after the first failure
rift-client-test: added 5-seconds request timeout. it is supposed to terminate get/post request on timeout
tests: indent cleanup
io: added iodevice index, which shows current iodevice to read from when handling client's /get/ request. this allows not to drop devices from 'themself', but instead iterate over array of iodevices (chunk requests to elliptics) and send data back to client when it is ready.
v2.25.0.10.2