Adds requests package installation to debian postinst

Change-Id: Ibeb270fce9cc0fe546da479a7c34981c4b918329
Signed-off-by: Benjamin Diaz <bdiaz@whitestack.com>
diff --git a/requirements.txt b/requirements.txt
index b31d0b0..3d22bdf 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,5 +4,5 @@
 pyyaml==3.*
 pymysql==0.9.*
 peewee-migrate==1.1.*
-requests
+requests==2.*
 git+https://osm.etsi.org/gerrit/osm/common.git@v5.0#egg=osm-common