Migrate to Pipenv, remove requirements.txt

In b1e6160 Pipenv was added to
Paperless, adding a note to the changelog in
eec8f09 that a switch to just using
Pipenv was planned.

This commit performs this switch. Having two sources for which
dependencies should be installed (requirements.txt, Pipfile.lock) is
very suboptimal, and the files have diverged since they have been added.

This closes the-paperless-project#661.

.gitignore

@@ -76,6 +76,7 @@ db.sqlite3-journal
 virtualenv
 docker-compose.yml
 docker-compose.env
+requirements.txt
 
 # Used for development
 scripts/import-for-development

docs/examples/lxc/lxc-install.sh

@@ -108,7 +108,9 @@ su -c "cd /home/paperless ; git clone https://github.com/the-paperless-project/p
 
 # Install Pip Requirements
 apt-get -y install python3-pip python3-venv
+pip3 install pipenv
 cd /home/paperless/paperless
+pipenv lock -r > requirements.txt
 pip3 install -r requirements.txt
 
 # Take paperless.conf.example and set consumuption dir (ftp dir)

docs/migrating.rst

@@ -82,6 +82,7 @@ rolled in as part of the update:
 
     $ cd /path/to/project
     $ git pull
+    $ pipenv lock -r > requirements.txt
     $ pip install -r requirements.txt
     $ cd src
     $ ./manage.py migrate

docs/requirements.rst

@@ -32,8 +32,7 @@ For the purposes of simplicity, ``python`` and ``pip`` is used everywhere to
 refer to their Python3 versions.
 
 In addition to the above, there are a number of Python requirements, all of
-which are listed in a file called ``requirements.txt`` in the project root
-directory.
+which are listed in a file called ``Pipfile`` in the project root directory.
 
 If you're not working on a virtual environment (like Docker), you
 should probably be using a virtualenv, but that's your call.  The reasons why
@@ -71,29 +70,44 @@ dependencies is easy:
 
 .. code:: bash
 
-    $ pip install --user --requirement /path/to/paperless/requirements.txt
+    $ cd /path/to/paperless
+    $ pipenv lock -r > requirements.txt
+    $ pip install --user --requirement requirements.txt
 
 This will download and install all of the requirements into
 ``${HOME}/.local``.  Remember that your distribution may be using ``pip3`` as
 mentioned above.
 
+If you don't have Pipenv installed, then you can install it using ``pip``:
+
+.. code:: Bash
+
+    $ pip install --user pipenv
+
 
 .. _requirements-virtualenv:
 
 Python-specific Requirements: Virtualenv
 ----------------------------------------
 
-Using a virtualenv for this is pretty straightforward: create a virtualenv,
-enter it, and install the requirements using the ``requirements.txt`` file:
+Using a virtualenv for Paperless is very easy, thanks to Pipenv. If you don't
+have Pipenv installed, then you can install it using ``pip``:
+
+.. code:: Bash
+
+    $ pip install --user pipenv
+
+With Pipenv available, it is trivial to create the virtual environment and
+install the requirements:
 
 .. code:: bash
 
-    $ virtualenv --python=/path/to/python3 /path/to/arbitrary/directory
-    $ . /path/to/arbitrary/directory/bin/activate
-    $ pip install  --requirement /path/to/paperless/requirements.txt
+    $ cd /path/to/paperless
+    $ pipenv --python 3
+    $ pipenv install
 
-Now you're ready to go.  Just remember to enter (activate) your virtualenv
-whenever you want to use Paperless.
+Now you're ready to go. Just remember to enter the virtual environment
+created by Pipenv using ``pipenv shell`` whenever you want to use Paperless.
 
 
 .. _requirements-documentation:
@@ -102,8 +116,8 @@ Documentation
 -------------
 
 As generation of the documentation is not required for the use of Paperless,
-dependencies for this process are not included in ``requirements.txt``.  If
-you'd like to generate your own docs locally, you'll need to:
+dependencies for this process are not included in ``Pipfile``. If you'd like
+to generate your own docs locally, you'll need to:
 
 .. code:: bash