Add Newlines to end of .gitignore files, specifically the new app skel

Even though I think the fight is a bit futile, it is considered best practice to have newlines at the end of all files.  At the request of meteor/meteor#7786, this commit adds newlines to the end of the new app skeleton `.gitignore` file.  These skel files are used when generating new meteor apps so this avoids perpetuation of this problem into futrue generations. ;)

In an effort to beef up this PR, I also took the liberty of fixing the few other Meteor files which were lacking newlines (all `.gitignore` files)

Closes meteor/meteor#7786

packages/.gitignore

@@ -1,2 +1,2 @@
 .meteor
-*/.meteor
+*/.meteor

packages/code-prettify/.gitignore

@@ -1,2 +1,2 @@
 .build*
-.!*
+.!*

scripts/admin/eslint/.gitignore

@@ -1 +1 @@
-node_modules
+node_modules

scripts/windows/.gitignore

@@ -1,4 +1,4 @@
 *.tar.gz
 *.exe
 *.pdb
-*_.cs
+*_.cs

tools/static-assets/skel/.gitignore

@@ -1 +1 @@
-node_modules/
+node_modules/

tools/tests/apps/shell/.gitignore

@@ -1 +1 @@
-node_modules/
+node_modules/