Make missing annotations None instead of empty dict

See merge request !135

Included metadata during the feature extraction.

See merge request !125

Created the method is_argument_available that checks if an argument is available for certain method. provided both python2 and python3 implementations

Used the new method is_argument_available

Used the new method is_argument_available

Improved the test cases

[sphinx] Documented the metadata info

Fixed issue in the projector metadata

Included metadata durint the feature extraction. Ongoing with cd workspace_HTFace/

Changed the paths to images

See merge request !134

Mentions bob.bio.vein on bob.bio.base docs (closes #104)

Closes #104

See merge request !133

Add annotator support

See merge request !131

This reverts commit 3fdb09c9.

Add missing test dependencies

See merge request !132