Update .travis.yml

.travis.yml

@@ -3,6 +3,8 @@ python:
   - "2.7"
 install:
   - pip install -r requirements.txt
+  - pip install lxml --upgrade
+  - pip install ftp://xmlsoft.org/libxml2/python/libxml2-python-2.6.21.tar.gz
   - pip install PyXmlSec --allow-external PyXMLSec --allow-insecure PyXMLSec
   - pip install coveralls
 script: