tang: Add package into tree

Tang is lightweight server for binding data to network presence.
---
Tang's source: https://github.com/latchset/tang

Maintainer: @Tiboris

Compile tested: (mips, TL-WR842N, 17.01.4, r3560-79f57e422d)

**Tang requires a few other software libraries:**

1. libhttp-parser
2. xinetd's socket activation
3. jose >= 8

**Two new files compared to tang upstream:**
- tangdx : configuration file for xinetd
- tangdw : wrapper for tangd service
	- puts timestamp when service activated, and
	- redirects stderr to log file in /var/log/

**Removed systemd requirement**

Signed-off-by: Tibor Dudlák <tdudlak@redhat.com>

utils/tang/patches/Makefile_am.patch

@@ -0,0 +1,45 @@
+diff --git a/Makefile.am b/Makefile.am
+index 14bf91d..dfa6d07 100644
+--- a/Makefile.am
++++ b/Makefile.am
+@@ -1,5 +1,3 @@
+-DISTCHECK_CONFIGURE_FLAGS = --with-systemdsystemunitdir=$$dc_install_base/$(systemdsystemunitdir)
+-
+ AM_CFLAGS = @TANG_CFLAGS@ @jose_CFLAGS@
+ LDADD = @jose_LIBS@ @http_parser_LIBS@
+ 
+@@ -7,21 +5,11 @@ nagiosdir = $(libdir)/nagios/plugins
+ cachedir = $(localstatedir)/cache/$(PACKAGE_NAME)
+ jwkdir = $(localstatedir)/db/$(PACKAGE_NAME)
+ 
+-nodist_systemdsystemunit_DATA = \
+-    units/tangd@.service \
+-    units/tangd.socket \
+-    units/tangd-update.path \
+-    units/tangd-update.service \
+-    units/tangd-keygen.service
+-
+ dist_libexec_SCRIPTS = src/tangd-update src/tangd-keygen
+ libexec_PROGRAMS = src/tangd
+-nagios_PROGRAMS = src/tang
+-man1_MANS = doc/tang-nagios.1
+ man8_MANS = doc/tang.8
+ 
+ src_tangd_SOURCES = src/http.c src/http.h src/tangd.c
+-src_tang_SOURCES = src/nagios.c
+ 
+ %: %.in
+ 	$(AM_V_GEN)mkdir -p "`dirname "$@"`"
+@@ -32,11 +20,9 @@ src_tang_SOURCES = src/nagios.c
+ 		$(srcdir)/$@.in > $@
+ 
+ AM_TESTS_ENVIRONMENT = SD_ACTIVATE="@SD_ACTIVATE@" PATH=$(srcdir)/src:$(builddir)/src:$(PATH)
+-TESTS = tests/adv tests/rec tests/nagios
++TESTS = tests/adv tests/rec 
+ 
+-CLEANFILES = $(nodist_systemdsystemunit_DATA)
+ EXTRA_DIST = \
+-    $(foreach unit,$(nodist_systemdsystemunit_DATA),$(unit).in) \
+     COPYING \
+     $(TESTS) \
+     $(man1_MANS) \