fix: Improve dependencies listing

Partial fix for #110

.travis.yml

@@ -21,10 +21,8 @@ install:
     - pip install coveralls
     - pip install codecov
     - pip install requests-mock
-    - pip install https://github.com/lief-project/packages/raw/lief-master-latest/pylief-0.7.0.dev.zip
     - pip install git+https://github.com/kbandla/pydeep.git
-    - pip install python-magic
-    - pip install .
+    - pip install .[fileobjects,neo,openioc]
     - pushd tests
     - git clone https://github.com/viper-framework/viper-test-files.git
     - popd

setup.py

@@ -28,6 +28,9 @@ setup(
     ],
     test_suite="tests.test_offline",
     install_requires=['six', 'requests', 'python-dateutil', 'jsonschema'],
+    extras_require={'fileobjects': ['lief>=0.8', 'python-magic'],
+                    'neo': ['py2neo'],
+                    'openioc': ['beautifulsoup4']},
     tests_require=[
         'jsonschema',
         'python-dateutil',