Update build scripts

Change-Id: I8d7d709858d6e8d9576aa387f8d2782579c5b210
configure.ac: The OpenWebRTC GStreamer plugins install no pkg-config file

And they are only a runtime dependency, no build dependency.
build: Don't use -pedantic and -ansi

They will fail the build too easily with external headers and don't do what
one would expect. Instead let autoconf figure out the right compiler flags for
using a standard conformant C compiler.
nice: Version 0.1.7.1 or newer is required to build
owr_local_media_source: Work around wrong compiler warning

owr_local_media_source.c: In function 'owr_local_media_source_get_pad':
owr_local_media_source.c:119:10: error: 'source' may be used uninitialized in this function [-Werror=maybe-uninitialized]
     if (!gst_element_link(a, b)) \
          ^
owr_local_media_source.c:296:17: note: 'source' was declared here
     GstElement *source, *capsfilter = NULL, *tee;
build: Requires gstreamer-app-1.0 and gstreamer-video-1.0 too
transport/owr_candidate: Use - instead of _ to prevent assertions with G_PARAM_STATIC_STRINGS
build: Fix linking of the bridge daemon
Require GStreamer >= 1.4 and write the version only once
build: Make sure we have the scripts submodule
Update scripts

A bug was fixed in the gst-plugins-bad build script

Change-Id: I1f353029ffddef42a7eec815a8aea602a55d4af2
libopenwebrtc.exp: Remove deprecated symbols

A work-in-progress plugin was removed from the build scripts which
caused some symbols to disappear. This patch just fixes the build of
OpenWebRTC after updating the build scripts.
Removed empty files
Removed empty files
configure.ac: Add foreign to AM_INIT_AUTOMAKE

This ignores missing standard GNU project files, like the empty text
files that were removed.
owr_video_renderer: add sink property

Make the video sink configurable at renderer creation time for further
flexibility. In some cases the default glimagesink can't be used. The
guintptr value should point to a valid GStreamer element.