Although the default value of defaultbranch is master I'm adding it
anyways.  This way when new major branches are being created the value
can be updated instead of having to remember the name of the key.

Change-Id: I3db009217c5ae399fb84bee95076f4dbb7fa52d2

Add the .gitignore and .gitreview files to the asterisk repo.

NB:  You can add local ignores to the .git/info/exclude file
without having to do a commit.

Common ignore patterns are in the top-level .gitignore file.
Subdirectory-specific ignore patterns are in their own .gitignore
files.

Change-Id: I842a1588ff27d8a0189f12d597f0a7af033d6c69
Tested-by: George Joseph