Dcoraid

- enh: improve spacing in GUI design (44)
- enh: make sure there are no uploads without RT-DC files
- fix: download in "My Data" tab did not work (42)
- ref: remove old code that cleared old cache and
get rid of the appdirs dependency
- setup: make pyqt5 an optional dependency (39)

- fix: skip passing emtpy-valued API-Key (41)
- enh: added logging capabilities (18)

- setup: bump dclab from 0.38.1 to 0.38.2 (40)

- ref: migrate to package_revise for updating datasets (28)
- setup: bump dclab from 0.37.2 to 0.38.1

- enh: add "create_task" function for generating custom .dcoraid-task
files in Python scripts
- fix: do not delete drafts that are in the upload queue (36)
- setup: bump dclab from 0.36.1 to 0.37.1

- fix: fatal typo in 0.7.4 release