python-pip: add site-wide pip.conf with defaults

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

lang/python-pip/Makefile

 
 PKG_NAME:=python-pip
 PKG_VERSION:=7.1.2
-PKG_RELEASE:=2
+PKG_RELEASE:=3
 
 PKG_SOURCE:=pip-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=https://pypi.python.org/packages/source/p/pip/
 endef
 
 define PyPackage/python-pip/install
-	$(INSTALL_DIR) $(1)/usr/bin
-	$(CP) $(PKG_INSTALL_DIR)/usr/bin/* $(1)/usr/bin
+	$(INSTALL_DIR) $(1)/usr/bin $(1)/etc
+	$(INSTALL_BIN) $(PKG_INSTALL_DIR)/usr/bin/* $(1)/usr/bin
+	$(INSTALL_CONF) ./files/pip.conf $(1)/etc/
 endef
 
 $(eval $(call PyPackage,python-pip))

lang/python-pip/files/pip.conf

+[global]
+cache-dir=/tmp/.cache
+log-file=/tmp/pip-log.txt