Merge pull request #13 from matvore/usr-int

Prepare hesokuri.main to implement some extra commands
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