AU: Bzip2 utility functions that mirror Gzip utility functions.

Also, Convert the gzip_unittest into a typed test and use the same
test cases for bzip2.

Review URL: http://codereview.chromium.org/855002
diff --git a/SConstruct b/SConstruct
index e27871a..8854abc 100644
--- a/SConstruct
+++ b/SConstruct
@@ -85,6 +85,7 @@
 
 
 sources = Split("""action_processor.cc
+                   bzip.cc
                    bzip_extent_writer.cc
                    cycle_breaker.cc
                    decompressing_file_writer.cc
@@ -125,7 +126,6 @@
                             filesystem_copier_action_unittest.cc
                             filesystem_iterator_unittest.cc
                             graph_utils_unittest.cc
-                            gzip_unittest.cc
                             http_fetcher_unittest.cc
                             mock_http_fetcher.cc
                             omaha_hash_calculator_unittest.cc
@@ -138,7 +138,8 @@
                             test_utils.cc
                             topological_sort_unittest.cc
                             update_check_action_unittest.cc
-                            utils_unittest.cc""")
+                            utils_unittest.cc
+                            zip_unittest.cc""")
 unittest_main = ['testrunner.cc']
 
 delta_generator_sources = Split("""delta_diff_generator.cc""")