Implement gitlab support

[bestxp]

Base provider for get gitlab file/tags

[coveralls]

Coverage decreased (-4.9%) to 85.21% when pulling ac98ec197dc6086a8fa6f3491ab5f7709e735362 on bestxp:master into d3d13fcedfa29b1bbb5c381d2071811dee0005b4 on stamm:master.

[codecov-io]

Codecov Report

Merging #24 into master will decrease coverage by 4.37%. The diff coverage is 14.28%.

@@            Coverage Diff             @@
##           master      #24      +/-   ##
==========================================
- Coverage   88.88%   84.51%   -4.38%     
==========================================
  Files          14       15       +1     
  Lines         450      478      +28     
==========================================
+ Hits          400      404       +4     
- Misses         43       67      +24     
  Partials        7        7

Impacted Files	Coverage Δ
providers/gitlab/provider.go	14.28% <14.28%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update d3d13fc...ac98ec1. Read the comment docs.