drop the "path" option support

[gre]

following up of #66 (comment) / #62 (comment)
need to deprecate "path" and release a major that drop it.

for moving files, use react-native-fs or CameraRoll.saveToCameraRoll

[brentvatne]

👍 makes sense to deprecate it to me

[gre]

at the same time, we should rename "file" to "tmpfile" to make it clear this is not going to be kept very long.
that way we can also deprecate any usage of that "file" at same time of "path"

[gre]

fixed in v2