Move the serialize utility method from repl.clj into util

Add a unit test, and clean up the existing unit tests in hesokuri.util-test.
Implement hesokuri.hesobase/init

Some refactoring was needed to write the test case:
- a public key test value was moved to hesokuri.testing.data
- hesokuri.repo/branches-and-hash-list was made public and, because it is useful
  in the context of Git in general, moved to hesokuri.git.
Implement the "init" command for the command-line interface
Merge branch 'master' into usr-int

Conflicts:
	src/hesokuri/git.clj
	src/hesokuri/hesobase.clj
	test/hesokuri/git_test.clj
	test/hesokuri/testing/data.clj
Indent multi-line docstrings of new functions

New functions meaning functions that haven't been merged into master yet.
Use hesokuri.git/Context rather than git-dir style

This feature was introduced in another branch and has since been merged into
master.

Also, add a missing comma.
Add another unit test for hesokuri.hesobase/init

This makes sure an exception is thrown if the hesobase already exists.
Merge pull request #16 from matvore/usr-int

Implement the "init" command for the command-line interface