First pass for community issue templates

* Include "Bug" template from the contribution guide
* Include "Feature Proposal" template from the contribution guide

.gitlab/issue_templates/Bug.md

+## Summary
+
+(Summarize your issue in one sentence - what goes wrong, what did you expect to happen)
+
+## Steps to reproduce
+
+(How one can reproduce the issue - this is very important)
+
+## Expected behavior
+
+(What you should see instead)
+
+## Relevant logs and/or screenshots
+
+(Paste any relevant logs - please use code blocks (```) to format console output,
+logs, and code as it's very hard to read otherwise.)
+
+## Output of checks
+
+### Results of GitLab Application Check
+
+(For installations with omnibus-gitlab package run and paste the output of:
+sudo gitlab-rake gitlab:check SANITIZE=true)
+
+(For installations from source run and paste the output of:
+sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true)
+
+(we will only investigate if the tests are passing)
+
+### Results of GitLab Environment Info
+
+(For installations with omnibus-gitlab package run and paste the output of:
+sudo gitlab-rake gitlab:env:info)
+
+(For installations from source run and paste the output of:
+sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production)
+
+## Possible fixes
+
+(If you can, link to the line of code that might be responsible for the problem)

.gitlab/issue_templates/Feature Proposal.md

+## Description
+Include problem, use cases, benefits, and/or goals
+
+## Proposal
+
+## Links / references