[loader] Change semantics of path in ini

[loader] Change semantics of path in ini

Ini description is expected to be somewhat determinisitic.

But paths inside ini is not deterministic. For example, if you have
save_path=model.bin,

if A application trains it and B application try to use it, reading the
same ini does not gaurantee B to read to the weights from A.

It is because A and B can have diffrent working path.

To make it consistent, this patch changes semantics of paths' in ini.

1. if model.appcontext.hasWorkingDirectory(), path inside ini are interpreted from
the workingDirectory
2. else, it is interpreted **relative to where ini is located at.**

**Self evaluation:**
1. Build test: [X]Passed [ ]Failed [ ]Skipped
2. Run test: [X]Passed [ ]Failed [ ]Skipped

Signed-off-by: Jihoon Lee <jhoon.it.lee@samsung.com>