Remove deps/ ignoring, since the directory no longer exists

Also ignore manifests and remove the one that was erroneously checked
in.

Author: ararslan

.gitignore

@@ -1,10 +1,6 @@
 *.jl.cov
 *.jl.*.cov
 *.jl.mem
-deps/deps.jl
-deps/build.log
-deps/downloads
-deps/usr
-deps/src
 docs/build
 docs/site
+Manifest.toml