TST: fix html table parser tests: install lxml

and mark viriback parser as exotic

.travis.yml

@@ -19,7 +19,7 @@ install:
   - set -e
   - if [[ -v requirements ]]; then sudo apt-get install polipo lighttpd; fi
   - if [[ $mode == debian ]]; then sudo apt-get install dpkg-dev dh-python python-setuptools python3-setuptools python3-all debhelper quilt fakeroot dh-systemd safe-rm; fi
-  - if [[ $requirements == true ]]; then for file in intelmq/bots/*/*/REQUIREMENTS.txt; do pip install -r $file; done; fi
+  - if [[ $requirements == true ]]; then for file in intelmq/bots/*/*/REQUIREMENTS.txt; do pip install -r $file; done; pip install lxml; fi
   - if [[ $TRAVIS_PYTHON_VERSION < '3.5' ]]; then sudo pip install typing; fi
   - if [[ -v requirements ]]; then pip install Cerberus!=1.3 codecov pyyaml; fi
   - if [[ $mode == codestyle ]]; then pip install pycodestyle; fi

docs/Feeds.md

@@ -1952,6 +1952,7 @@ To add feeds to this file add them to `intelmq/etc/feeds.yaml` and then run
 * **Status:** on
 * **Revision:** 27-06-2018
 * **Description:** Latest detected unsafe sites.
+* **Additional Information:** You need to install the lxml library in order to parse this feed.
 
 ### Collector
 

intelmq/etc/feeds.yaml

@@ -3,7 +3,7 @@ providers:
   ViriBack:
     Unsafe sites:
       description: Latest detected unsafe sites.
-      additional_information:
+      additional_information: You need to install the lxml library in order to parse this feed.
       bots:
         collector:
           module: intelmq.bots.collectors.http.collector_http

intelmq/tests/bots/parsers/html_table/test_viriback.py

@@ -53,6 +53,7 @@
           "feed.name": "Viriback"}
 
 
+@test.skip_exotic()
 class TestHTMLTableParserBot(test.BotTestCase, unittest.TestCase):
 
     @classmethod