cli: printer initial release

[ParthS007]

• replace print() and click.echo() with display_message()

closes #61

[codecov-io]

Codecov Report

Merging #70 into master will increase coverage by 0.15%. The diff coverage is 76.66%.

@@            Coverage Diff             @@
##           master      #70      +/-   ##
==========================================
+ Coverage   89.91%   90.07%   +0.15%     
==========================================
  Files           9       10       +1     
  Lines         367      393      +26     
==========================================
+ Hits          330      354      +24     
- Misses         37       39       +2     

Impacted Files	Coverage Δ
cernopendata_client/searcher.py	76.92% <20.00%> (-0.75%)	:arrow_down:
cernopendata_client/cli.py	89.55% <72.22%> (+0.07%)	:arrow_up:
cernopendata_client/printer.py	94.11% <94.11%> (ø)
cernopendata_client/config.py	100.00% <100.00%> (ø)
cernopendata_client/downloader.py	100.00% <100.00%> (ø)
cernopendata_client/utils.py	100.00% <100.00%> (ø)
cernopendata_client/validator.py	100.00% <100.00%> (ø)
cernopendata_client/verifier.py	100.00% <100.00%> (ø)