PAINTROID-388 import images via overflow menu

[Tscheppe]

Added Submenu in Load Image in the overflow menu to replace the image and to import a image to the current layer

https://jira.catrob.at/browse/PAINTROID-388

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[Electronix1337]

I think you have to change some other tests too, as they are failing on Jenkins as well as locally. For instance the test testLoadWithoutChange() in OpenedFromPocketCodeNewImageTest.java file fails, but I tried adding
onView(withText(R.string.menu_replace_image)).perform(click());
after clicking on load image and then the tests passes. So please check locally which tests are failing and fix them.

[Electronix1337]

LGTM, even though on my local machine most of the MenuFileActivityIntegrationTest fail, this should not happen due to these changes.

[wslany]

Thanks!