Recognize Recommends relations of RPMs

Recognize Recommends relations of RPMs

When there are multiple candidate packages as a result of
Provides, the current obs-build gives an error: "have choice for".

However, according to http://www.rpm.org/wiki/PackagerDocs/Dependencies ,
Recommends tells the system to install the corresponding package
unless there is a conflict; thus, if there is a package recommended
(as described in issue #302), obs-build shall install the recommended
package, resolving "have choice for" error.

To enable, OBS project should declare:
"BuildFlags: UseRecommendsForChoices=1"
or
"BuildFlags: UseRecommendsForChoices"
in its project config.

Fixes #302

Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Conflicts:
	createdirdeps
	expanddeps

Change-Id: I65dc6dd16a6874b7c1ae47932d37c23ec98b9cdf