PyTest: add testProperties

* Contains 2 nose-tests:
     * testAddMetadataDate: add metadata 'date' to the outputFile.
     * testAddMetadataPlo: check if metadata 'plop' is not added to the
outputFile.
PyTest: add testTranscoder for dummy/rewrap/transcode

* Add 6 nose-tests about dummy.
* Add 2 nose-tests about rewrap.
* Add 6 nose-tests about transcode.
Raname InputStream / OutputStream classes: add prefix "I" for "interface"

* Need to do it for other interface.
* Need to rename InputStream / OutputStream files accordingly.
Raname InputStream / OutputStream files: add prefix "I" for "interface"
InputStream: add private function getAVStream
OutputStream: remove default constructor

* AvOutputStream: no sense to create a default outputStream and can't
set its output file or stream index.
* IOutputStream: remove default constructor (automatically generated).
InputStream: remove default constructor

* AvInputStream: no sense to create a default inputStream and can't set
its input file or stream index.
* IInputStream: remove default constructor (automatically generated).
Rename EssenceTransform class to IEssenceTransform

Add prefix "I" for "interface".
Rename EssenceTransform file to IEssenceTransform

According to the name of the class contains in the file.
CodedStream folder: to lowerCamelCase
EssenceStream folder: to lowerCamelCase
EssenceTransform folder: to lowerCamelCase
File folder: to lowerCamelCase
CMake avplay: do not build the app if OpenGL or GLUT are not found

* Print a warning if avplay app can't be built.
* Allow the user to build avTranscoder library even if dependencies of
this app are not found.
* fix #94
Merge pull request #98 from cchampet/build_avplay_optionnal

CMake avplay: do not build the app if OpenGL or GLUT are not found
ProgressListener: add IProgress class

* Base class of all possible Progress.
* ProgressListener inherits this base class.
* Add documentation.
* Swig: add feature "director" to the base class.
ProgressListener: rename ProgressListener to ConsoleProgress

the class implements the IProgress, to display a progress bar in
console.
ProgressListener: add NoDisplayProgress class

* Manage cases when we need an IProgress but don't care of a progress
bar.
* Use it in avMeta app: we want the file infos, but don't care of the
progress bar.
ProgressListener: separate interface from implementation

* Create ProgressListener.cpp.
* Add include to iostream in Transcoder.
Add progress folder

* Contains all files related to the progress.
* Also contains corresponding swig interface file.