Options --dirname-pattern and --filename-pattern

Instaloader downloads all posts in

  <DIRNAME>/<FILENAME>+(suffix and extension)

which are now generated by the templates given with --dirname-pattern
and --filename-pattern. These templates may contain specifiers such as
'{target}', '{profile}', '{date}' and '{shortcode}'.

Default for --dirname-pattern is '{target}', default for
--filename-pattern is '{date:%Y-%m-%d_%H-%M-%S}'

The former options --no-profile-subdir and --hashtag-username were
removed, because their behavior can now be achieved like this:

--no-profile-subdir and --hashtag-username:
--dirname-pattern='.' --filename-pattern='{profile}__{date:%Y-%m-%d_%H-%M-%S}'

--no-profile-subdir, but not --hashtag-username:
--dirname-pattern='.' --filename-pattern='{target}__{date:%Y-%m-%d_%H-%M-%S}'

--hashtag-username but not --no-profile-subdir:
--dirname-pattern='{profile}'

This adds the option proposed in #23, to encode both the hashtag and the
profile name in the file's path when downloading by hashtag, e.g.:
--dirname-pattern='{target}' --filename-pattern='{profile}_{date:%Y-%m-%d_%H-%M-%S}'

(Closes #23)

.travis.yml

@@ -9,4 +9,4 @@ python:
 install:
  - pip install pylint requests
 script:
- - python3 -m pylint -r n -d bad-whitespace,missing-docstring,too-many-arguments,locally-disabled,line-too-long,too-many-public-methods,too-many-lines instaloader
+ - python3 -m pylint -r n -d bad-whitespace,missing-docstring,too-many-arguments,locally-disabled,line-too-long,too-many-public-methods,too-many-lines,too-many-instance-attributes instaloader