Update coverage submission.

Author: fredrikekre

.gitignore

@@ -1 +1,2 @@
 /Manifest.toml
+/test/coverage/Manifest.toml

.travis.yml

@@ -15,4 +15,5 @@ notifications:
   email: false
 
 after_success:
-    - julia -e 'cd(Pkg.dir("Quaternions")); Pkg.add("Coverage"); using Coverage; Coveralls.submit(Coveralls.process_folder())'
+    - julia --project=test/coverage -e 'using Pkg; Pkg.instantiate();
+          using Coverage; Coveralls.submit(Coveralls.process_folder())'

test/coverage/Project.toml

@@ -0,0 +1,2 @@
+[deps]
+Coverage = "a2441757-f6aa-5fb2-8edb-039e3f45d037"