add www/img/logo.png file in order to pass file.spec.147 tests

Platforms affected

each platforms

Motivation and Context

createmobilespec command here creates a test project mobilespec. In that test project, the cordova-plugin-file-test plugin is added. (cordova-plugin-file-test is a part of cordova-plugin-file) test.js in cordova-plufin-file-tests checks /www/img/logo.png file exists or not, as

                    resolveLocalFileSystemURL('cdvfile://localhost/' + cdvfileApplicationDirectoryFsRootName + '/www/img/logo.png', function (entry) {
 ...

in file.spec.147.

Therefore the project must have a file www/img/logo.png file to pass the tests.

Description

This PR simply added www/img/logo.png file in order to pass the file.spec.147 in cordova-plugin-file-tests.

Testing

launching mobilespec project as

./cordova run android

in mobilespec directory. Confirm jasmine tests.

Checklist

[ ] I've run the tests to see all new and existing tests pass
[ ] I added automated test coverage as appropriate for this change
[ ] Commit is prefixed with (platform) if this change only applies to one platform (e.g. (android))
[ ] If this Pull Request resolves an issue, I linked to the issue in the text above (and used the correct keyword to close issues using keywords)
[ ] I've updated the documentation if necessary

apache / cordova-mobile-spec