Elm theme: correct parse a theme filename on Windows OS.

Elm theme: correct parse a theme filename on Windows OS.

Windows os uses ':'  as delimiter between disk name and file path.
<disk>:/<dir>/file.ext. In this commit added parse case for <disk_name>
symbol meets before ":/".

Merged with commit:
commit fd7ec0acfdb20888bfe8a827ef6141193380f3ff
Author: Mykyta Biliavskyi <m.biliavskyi@samsung.com>
Date:   Fri Oct 21 15:46:49 2016 +0300

Elm_theme: parse theme name "<disk>:/file.ext" only on Windows.

Commit 86928a430c broke ability to use more than one theme file for
posix compatible systems. For case
ELM_THEME=/home/user/a.edj:/home/user/b.edj string was parsed
incorrectly. The result was a single string
"/home/user/a.edj:/home/user/b.edj", but expected two strings
"/home/user/a.edj" and "/home/user/b.edj"

This commit add additional check of the file paths like
<disk>:/filename.ext or <disk>:\filename.ext in Windows only.
This avoid wrong parse behaviour on Linux and macOS.

Change-Id: I40f6e79209ef4eb38a6e892447b4b7930b9ccf1a
Signed-off-by: Mykyta Biliavskyi <m.biliavskyi@samsung.com>