devel/py-pbr: Add pip to RUN_DEPENDS as swift and swiftclient need it

swift and swiftclient depend on pbr, output errors on import when pip is
not available at runtime, but don't explicitly declare a dependency on pip
themselves.

While implicit dependencies are not good practice, pbr does declare pip in its
requirements, which is not reflected in this ports RUN_DEPENDS. So:

- Add py-pip to RUN_DEPENDS

Reported by:	trociny

devel/py-pbr/Makefile

@@ -3,6 +3,7 @@
 
 PORTNAME=	pbr
 PORTVERSION=	0.5.23
+PORTREVISION=	1
 CATEGORIES=	devel python
 MASTER_SITES=	CHEESESHOP
 PKGNAMEPREFIX=	${PYTHON_PKGNAMEPREFIX}
@@ -12,6 +13,8 @@ COMMENT=	Python Build Reasonableness
 
 LICENSE=	AL2
 
+RUN_DEPENDS=	${PYTHON_PKGNAMEPREFIX}pip>=1.0:${PORTSDIR}/devel/py-pip
+
 USE_PYTHON=		yes
 USE_PYDISTUTILS=	easy_install
 PYDISTUTILS_AUTOPLIST=	yes