merge stable back to support `git describe`
example of log configuration in JSON format

log::Target::File auxiliary methods (getters and setters)
minor documentation changes
bump doxygen doxumentation version

websocket as basic tools` subpage
HTTP module bug fix: 'query' part was missed in the http request first line

http: request first line should contain 'path' and 'query' parts
log: avoid streamsize to size_t warning
support 'timestamp' parameter for a "command/poll" request

update cloud6::Command to support 'timestamp' property (UTC date and time as simple string)
update simple_dev/simple_gw/zigbee_gw examples (REST) to support the last received command timestamp

NOTE: this 'timestamp' is valid during application lifetime only, to be able to process "offline" commands (which are received by server while application is not running) this 'timestamp' parameter should be saved between application runs.
support for device's custom data
support for /info request which returns server information

"serverTimestamp" is used to start polling commands from the gateway starting time
use full 'hive::log::*' references instead of short 'log::*'

simple 'log::' expression confuses some old gcc compilers, in that case 'log' is ambiguous because of log() function from math.h

there are three different workarounds:
 - use full classified names like 'hive::log::Logger a;'
 - use 'using namespace hive::log; Logger a;'
 - use 'namespace L = hive::log; L::Logger a;'
bug fix: notification's parameters were in surrounding "parameters" object

was:
notification: {
  parameters: {
    parameters: {      // <<< this one "parameters" removed
      state: true
    }
  }                    // <<<
}
use case insensitive comparison for device identifiers
write unhandled exceptions to the log file
DelayedTasks mix-in class introduced

now it's possible to use callLater() method for delayed tasks (such as register again or poll commands again)
all REST examples (simple_dev, simple_gw, zigbee_gw) are updated
minor documentation fixes
introduce cloud6::ServerAPI::setTimeout() method to change default WEB timeout and --web-timeout command line argument
use REST API by default instead of websocket
introduce "Authorization" header name and Request::isStatusSuccessful() auxiliary method
local DNS cache introduced
use binary log file to prevent replacement of '\n' to '\r\n' on Windows
the way that resolve information is displayed has been changed - one line is used now
json::toStrHH() function has been introduced which writes JSON value without quotes if possible