Added contribution guide and require DCO

Signed-off-by: Nikos Mavrogiannopoulos <nmav@redhat.com>

CONTRIBUTING.md

@@ -0,0 +1,46 @@
+# ocserv -- Information about our contribution rules and coding style
+
+ Anyone is welcome to contribute to ocserv. You can either take up
+tasks from our [planned list](https://gitlab.com/ocserv/ocserv/milestones),
+or suprise us with enhancement we didn't plan for. In all cases be prepared
+to defend and justify your enhancements, and get through few rounds
+of changes. 
+
+We try to stick to the following rules, so when contributing please
+try to follow them too.
+
+# Git commits:
+
+Note that when contributing code you will need to assert that the contribution is
+in accordance to the "Developer's Certificate of Origin" as found in the 
+file [DCO.txt](doc/DCO.txt).
+
+To indicate that, make sure that your contributions (patches or merge requests),
+contain a "Signed-off-by" line, with your real name and e-mail address. 
+To automate the process use "git am -s" to produce patches and/or set the
+a template to simplify this process, as follows.
+
+```
+$ echo "Signed-off-by: My Full Name <email@example.com>" > ~/.git-template
+$ git config commit.template ~/.git-template
+```
+
+# Test suite:
+
+   New functionality should be accompanied by a test case which verifies
+the correctness of ocserv operation on successful use of the new
+functionality, as well as on fail cases. The test suite is run on "make check"
+on every system ocserv is installed, except for the tests/suite part
+which is only run during development.
+
+# C dialect:
+
+  All code in ocserv is expected to conform to C99.
+
+
+# Indentation style:
+
+ In general, use the Linux kernel coding style.  You may indent the source
+using GNU indent, e.g. "indent -linux *.c".
+
+

Makefile.am

@@ -1,5 +1,5 @@
 AUTOMAKE_OPTIONS = foreign
-EXTRA_DIST = LICENSE README.md
+EXTRA_DIST = LICENSE README.md CONTRIBUTING.md
 
 SUBDIRS = gl
 if NEED_LIBOPTS

doc/DCO.txt

@@ -0,0 +1,25 @@
+Developer's Certificate of Origin 1.1
+
+By making a contribution to this project, I certify that:
+
+(a) The contribution was created in whole or in part by me and I
+    have the right to submit it under the open source license
+    indicated in the file; or
+
+(b) The contribution is based upon previous work that, to the best
+    of my knowledge, is covered under an appropriate open source
+    license and I have the right under that license to submit that
+    work with modifications, whether created in whole or in part
+    by me, under the same open source license (unless I am
+    permitted to submit under a different license), as indicated
+    in the file; or
+
+(c) The contribution was provided directly to me by some other
+    person who certified (a), (b) or (c) and I have not modified
+    it.
+
+(d) I understand and agree that this project and the contribution
+    are public and that a record of the contribution (including all
+    personal information I submit with it, including my sign-off) is
+    maintained indefinitely and may be redistributed consistent with
+    this project or the open source license(s) involved.

doc/Makefile.am

@@ -1,7 +1,7 @@
 EXTRA_DIST = design.dia sample.config scripts/ocserv-script sample.passwd \
 	systemd/socket-activated/ocserv.service  systemd/standalone/ocserv.service \
 	systemd/socket-activated/ocserv.socket README-radius.md \
-	profile.xml sample.otp
+	profile.xml sample.otp DCO.txt
 
 dist_man_MANS = ocserv.8 ocpasswd.8 occtl.8