Remove build output and add standard .gitignore

It is my understanding that most Github projects do not include build output (i.e., iCloud.framework) in the code repository. The reason for this is that when I include the iCloudDocumentSync project in my project as a  dependent sub-project, the iCloudDocumentSync git submodule is dirtied every time the sub-project gets rebuilt (which occurs frequently because the sub-project is rebuilt when my main project is rebuilt).

If you are looking for a solution to host your binary, Github provides functionality to do so at this link: https://github.com/iRareMedia/iCloudDocumentSync/releases/new