[Convert] Support RSTRIDE = RU4 Cases (RGB && width%4>0)

[Convert] Support RSTRIDE = RU4 Cases (RGB && width%4>0)

Most (if not all) video/x-raw formats align data with 4-bytes for each
image row.

E.g., if image width = 642 and colorspace = RGB, video/x-raw adds
two zero-bytes for each row's end.

The tensor array should not have such zero-padding; thus
this commit supports zero-padding removal.

However, such operation costs one additional full memcpy; thus,
having such stream input must be discouraged.

This commit includes:
1. Support zero-padding removal
2. Added warnings when zero-paddings exists in the source streams.

Fixes #7

Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>