Change directory before switching branches

Running submodule update --init will error unless you are in your projects
TLD. Uses `git rev-parse --show-toplevel` to get the projects TLD.

git.rb

@@ -142,9 +142,14 @@ def self.stashes
    end
 
    def self.switch_branch(branch)
+      # capture only the path, not the newline
+      basedir = `git rev-parse --show-toplevel`.split("\n").first
+
+      # change directory to base dir
+      Dir.chdir(basedir)
+
       self.run_safe("git checkout \"#{branch}\"")
       self.run_safe("git submodule --quiet update --init --recursive")
-
       self.run_safe("git clean -ffd") if ARGV.include?('--clean')
 
       self.show_stashes_saved_on(branch)