Remove REPO_SLUG setting from private tests.

An existing repository is no longer required to do private tests.

It breaks test RepositoryAuthenticatedMethodsTest.test_archive as a repository needs at least one commit to be downloadable.

Signed-off-by: Baptiste Millou <baptiste@smoothie-creative.com>
Merge branch 'master' of git://github.com/davidmpaz/BitBucket-api into davidmpaz-master

Signed-off-by: Baptiste Millou <baptiste@smoothie-creative.com>

Conflicts:
	bitbucket/tests/private/__init__.py
Update doctstrings and way to launch private tests.

Launch private tests with : `site-packages$> python -m bitbucket.tests.private` .

Signed-off-by: Baptiste Millou <baptiste@smoothie-creative.com>
Update BitbucketAuthenticatedMethodsTest's test_get_tags and test_get_branches methods.

Signed-off-by: Baptiste Millou <baptiste@smoothie-creative.com>
Refactor testing of repository download as archive.

+ Add sh requirement
+ Clean requirements.txt
+ Update README.md and setup.py

- Probably break this test for windows

Signed-off-by: Baptiste Millou <baptiste@smoothie-creative.com>