Include Gemfile.lock, make build more verbose for CI.

Merged username-removed-25042 requested to merge pserwylo/fdroid-website:build-improvements into master

The Gemfile.lock is designed to be committed to version control:

http://yehudakatz.com/2010/12/16/clarifying-the-roles-of-the-gemspec-and-gemfile/

It pins down dependency versions, and is only updated when a dev explicitly asks for it to be. If it is not present, then the latest version of each dep will be included each time a bundle install is run.

This relates to the build failure in #55 (closed). If I have jekyll-paginate-v2 pinned to v1.7.3 then it works. If I let it get chosen by bundle install then we get v1.7.4 and it fails. Thus, the Gemfile.lock in this commit includes v1.7.3.

As one final improvement, it also makes the build be more verbose so that better output is shown when a failure does happen (--verbose --trace).

(Sort of) fixes #55 (closed). It doesn't properly, because at some point we probably want to upgrade this dependency, and at that point, we will run into the problem again. But at least for now we can continue to run CI and accept MRs.