PIM-1436 Described directory tree of exported media
PIM-1436 Export media in a computed sub-directory
PIM-1436 Associated ProductValue and PIM Media
Removed unused use statement
PIM-1436 Updated the changelog
Merge branch 'master' into feature/pim-1436

Conflicts:
	CHANGELOG.md
	features/Context/FixturesContext.php
PIM-1436 Fixed use statement in fixtures context
PIM-1436 Fixed show media action

Inheritance without defining doctrine mapping leads to undesired
behaviour like "SELECT t0. ...... FROM pim_catalog_media t0 WHERE t1...
= ...."
PIM-1436 Replaced oro Media by the akeneo Media
Merge pull request #424 from akeneo/feature/pim-1436

PIM-1436 Place exported media in different sub directories