mv_machine_learning: move meta directory into common one

mv_machine_learning: move meta directory into common one

[Issue type] : code cleanup

Move meta directory into common one. The meta directory contains
common code to parse task own config and meta information from given files
including preprocessing and postprocessing.

However, current directory structure made it to build each task group
with the code in meta directory. It led building-duplication.

Therefore, this patch moves the meta directory into common one to combine
meta and common code. As a reault, common directory will provide one so
library - mv_ml_common.so - to each task group, and the each task group
will include only relevant header files in the common and meta directories.

Change-Id: Ib9172761ddaad0b9044f6ec02cfc71dfecb59890
Signed-off-by: Inki Dae <inki.dae@samsung.com>