Auto merge of #1625 - alexcrichton:ignore-dotfile, r=brson

Whenever Cargo infers various targets for a project it currently picks up all
files in associated folders, but dotfiles are a common example of files which
editors generate which Cargo should not pick up, so this commit ignores all
dotfiles in the folders that it is looking at.

Closes #1615

diff --cc src/cargo/util/toml.rs
Simple merge

diff --cc tests/test_cargo_compile.rs
Simple merge