Switch commoncpp2 to ucommon to solve dependency conflicts.

libccrtp was depending on commoncpp2, and have been replaced by a version
depending on ucommon as well.
diff --git a/jni/libccrtp/sources/demo/.cvsignore b/jni/libccrtp/sources/demo/.cvsignore
new file mode 100644
index 0000000..f9c50a8
--- /dev/null
+++ b/jni/libccrtp/sources/demo/.cvsignore
@@ -0,0 +1,10 @@
+# ignore genorated...
+
+Makefile
+config.h
+Makefile.in
+*.lo
+*.la
+.libs
+stamp-h
+*.tmp