add select2 to app specific thirdparty

apps/files_external/3rdparty/select2/.gitignore

apps/files_external/3rdparty/select2/LICENSE

apps/files_external/3rdparty/select2/README.md

apps/files_external/3rdparty/select2/bower.json

apps/files_external/3rdparty/select2/component.json

apps/files_external/3rdparty/select2/composer.json

apps/files_external/3rdparty/select2/package.json

apps/files_external/3rdparty/select2/release.sh

apps/files_external/3rdparty/select2/select2-bootstrap.css

apps/files_external/3rdparty/select2/select2-spinner.gif

apps/files_external/3rdparty/select2/select2.css

apps/files_external/3rdparty/select2/select2.jquery.json

apps/files_external/3rdparty/select2/select2.js

apps/files_external/3rdparty/select2/select2.min.js

apps/files_external/3rdparty/select2/select2.png

apps/files_external/3rdparty/select2/select2_locale_ar.js

apps/files_external/3rdparty/select2/select2_locale_bg.js

apps/files_external/3rdparty/select2/select2_locale_ca.js

apps/files_external/3rdparty/select2/select2_locale_cs.js

apps/files_external/3rdparty/select2/select2_locale_da.js