bower2nix: 2.1.0 -> 3.0.1

1. Update bower2nix version and add new/updated dependencies into
   node-packages-generated.nix. This was done manually, with npm2nix
   generating the initial set of derivations. In future, it would be
   nice to have an automatic process (see #10358, #9332).

2. Add an override to nodePackages.bower2nix wrapping the commands so
   that git is on the PATH.

3. Update fetchbower to support new command-line options of bower2nix,
   and to allow github URL tag versions.

pkgs/top-level/node-packages.json

@@ -122,7 +122,6 @@
 , "git-run"
 , "bower"
 , "bower2nix"
-, "fetch-bower"
 , "npm-check-updates"
 , "node-stringprep"
 , "ltx"