Read and parse configuration files. Fixes #41. (#42)

Read and parse configuration files. Fixes #41.

 * supports nDPId / nDPIsrvd via command line parameter `-f`
 * nDPId: read general/tuning and libnDPI settings
 * support for settings risk domains libnDPI option via config file or via `-R` (Fixes #45, thanks to @UnveilTech)
 * added some documentation in the config file
 * adjusted Systemd and Debian packaging to make use of config files

Signed-off-by: Toni Uhlig <matzeton@googlemail.com>

ndpisrvd.conf.example

@@ -0,0 +1,31 @@
+[general]
+#pidfile                = /tmp/ndpisrvd.pid
+#user                   = nobody
+#group                  = nogroup
+
+# Collector listener as UNIX socket
+#collector              = /run/nDPIsrvd/collector
+
+# Distributor listener as UNIX socket
+#distributor-unix       = /run/nDPIsrvd/distributor
+
+# Distributor listener as IP socket
+#distributor-in         = 127.0.0.1:7000
+
+# Change group of the collector socket
+#collector-group        = daemon
+
+# Change group of the distirbutor socket
+#distirbutor-group      = staff
+
+# Max (distributor) clients allowed to connect to nDPIsrvd
+max-remote-descriptors = 128
+
+# Additional output buffers useful if a distributor sink speed unstable
+max-write-buffers      = 1024
+
+# Fallback to blocking I/O if output buffers full
+blocking-io-fallback   = true
+
+# Force poll() on systems that support epoll() as well
+#poll                   = false