spinner: add entry filter for accepted only digits and "."

spinner: add entry filter for accepted only digits and "."

Summary:
When spinner activated with entry, user can input any characters in entry.
It degrades the usability.

Add filter for only can input numbers and "." for case of decimal point existing.

I will add entry filter for limit size as well after this commit.
This spinner features may help for app developer and users too.

@feature

Test Plan:
Run elementary_test
Test various spinner format for check this.

Reviewers: Hermet, cedric

Subscribers: id213sin, shilpasingh

Differential Revision: https://phab.enlightenment.org/D3299

Signed-off-by: Cedric BAIL <cedric@osg.samsung.com>
Change-Id: I19c656584b940039efcae0d3bacba1380d5bd5ca