Merge branch 'copyright' into 'develop'

Update copyright note

See merge request ispconfig/ispconfig3!1153

LICENSE

-Copyright (c) 2007-2016, Till Brehm, ISPConfig UG
+Copyright (c) 2007-2020, Till Brehm, ISPConfig UG
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without modification,
@@ -22,4 +22,4 @@ BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
-EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
\ No newline at end of file
+EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.