erasure-code: move source files to a dedicated directory

The src/erasure-code directory contains the erasure-code plugin system
and the jerasure plugin. It is moved out of OSD because it now belongs
to a convenience library ( LIBERASURE_CODE ) which is used both by OSDs
and MONs.

Signed-off-by: Loic Dachary <loic@dachary.org>
erasure-code: move test files to a dedicated directory

Signed-off-by: Loic Dachary <loic@dachary.org>
Merge pull request #1194 from dachary/wip-erasure-code-directory

erasure code directory

Reviewed-By: Christophe Courtaut <christophe.courtaut@gmail.com>