tests/integration: adds image_filename in the test generation macro
integration: add paused pipeline seek tests
integration: add seek tests to paused pipeline (no playing)

This second set of seeking tests performs the seeks in a PAUSED
pipeline. After all seeks are successful, the pipeline is resumed so that the
test does not timeout.

Conflicts:
	tests/check/ges/integration.c
tests/integration: add an asset directory.
tests/integration: display test name when running it.
integration: add mixing tests

Add a new test that creates a given number of layers. Each layer has the same
assets / clips shifted by a different amount in the timeline. Alpha and volume
properties are different for each layer. This test is similar to the mixer
example in:

http://gist.github.com/MathieuDuponchelle/5736992#file-mixit-py

We should be able to add more clips to each layer, but this example test only
tests mixing 1 clip across 4 layers.

Conflicts:
	tests/check/ges/integration.c
tests: integration: Do not forget to set encoding profiles
tests: integration: Avoid leak
Fix compilation
timeline: Add support for group-id in the stream-start event
tests: integration: Make it possible to list all avalaible tests

You can not use make check-integration --list-tests, you have to use
./integration --list-tests instead
tests: check: All assets moved to assets/
tests: integration: Only use 2 layers for the mixing for now

+ Call the TSuite "integration" instead of "render"
build: add subdir-objects to AM_INIT_AUTOMAKE

Fixes warnings with automake 1.14

https://bugzilla.gnome.org/show_bug.cgi?id=705350