fix bullets for site markdown processor

[ci skip]
whitespace
patchlevel support for ruby DSL
cleanup
Initial adding of X.509 client certs
explain why parallel installs might break

[ci skip]
Adding documentation
Clarifying docs that client cert also should have key
Last time, getting the wording right.
Fixing the way we load the cert and key.

Turns out, you have to read the cert into Net::Http.cert.
Helps if I also document the environment vars...
make bundler gem accessible when building a gem
don't print "Installed" messaging
move ui messaging out of sources
show which worker the install came from in DEBUG mode
Version 1.4.0.pre.2 changelog
Merge pull request #2612 from snackbandit/509

Initial support of X.509 client certificates
Require version file for checking capistrano version

bundler-1.4.0.pre.1 works fine, but bundler-1.4.0.pre.2 shows error below:
```
$ bundle exec cap production deploy
/path/to/bundler-1.4.0.pre.2/lib/bundler/capistrano.rb:7:in `<top (required)>': uninitialized constant Capistrano::Version (NameError)
```

This commit brings this error, so I add require version file.
1d7a7893dfeb85afa25a3a526354b31c85f05dbf

bundler: 1.4.0.pre.2
capistrano: 2.14.2
Guard from load error 'capistrano/version'
Simple check const exist