COOK-2360: don't overwrite the epel repo if it already exists

commit 89e6c61b559caa1878eebf374ba971842111 changed the behavior of
the epel recipe to create instead of adding the epel repo file.  This
caused the file to be overwritten which changes the behavior from
previous.

COOK-2196 makes no mention of the need for this change.
COOK-2399 Foodcritic fixes for yum cookbook
COOK-2189 fix yum::ius dependency upon epel-release
Merge pull request #34 from juliandunn/COOK-2189-iusfix

[COOK-2189] fix yum::ius dependency upon epel-release
Merge pull request #33 from juliandunn/COOK-2399-foodcritic

[COOK-2399] Foodcritic fixes for yum cookbook
adding ability to set priority in repo file
Merge pull request #37 from sbates/retry-add_repo_priority_option

adding ability to set priority in repo file
[COOK-2519] - allow string for priority
initial support for test kitchen 1.0 alpha
add minitest, recipes for suites
move test cookbook up a dir, add to kitchen/berks
fixes for test kitchen 1.0 alpha support

* Use yum recipe directly on each suite to ensure providers are loaded
under chef-solo (related to
http://tickets.opscode.com/browse/CHEF-3376)
* Constrain berkshelf to 1.2.1 until vagrant 1.1 support is added
* corrected test cookbook name in its metadata
Merge branch 'tk-1.0-alpha'
[COOK-2643] - remove conditional attribute, use unless
release v2.2.0
increment version for development
[COOK-2639] - Add in yum epel baseurl attribute

  * Add in an attribute for epel to use for baseurl
add yum::elrepo.
Merge pull request #38 from jwitrick/master

Stop recipe from using url as mirrorlist
[COOK-2663] - add metadata_expire

 * Extend the LWRP to include metadata_expire
 * Update the template file for the expire setting