Do not push docker image with dev tag to quay.io

[juhoinkinen]

The image intended for development (i.e. one including the installed dev packages of Pipfile and pytest) was automatically build by drone and pushed to quay.io with the dev tag. However, that tag name could cause confusion (especially when tags with release versions will come to use).

This PR removes the drone step for building and publishing dev image, and the instructions in Wiki for using docker for development is updated with instructions to manually build the image for development.

Also removes unnecessary full-access to everyone for source code in image.

[codecov]

Codecov Report

Merging #323 into master will decrease coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #323      +/-   ##
==========================================
- Coverage   99.48%   99.45%   -0.04%     
==========================================
  Files          56       56              
  Lines        2929     2943      +14     
==========================================
+ Hits         2914     2927      +13     
- Misses         15       16       +1

Impacted Files	Coverage Δ
annif/exception.py	97.14% <0%> (-2.86%)	⬇️

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