Fix padrino-cache example comment

If memcache server is specified, it must be set options hash with `:server` key
ref: https://github.com/minad/moneta#creating-a-store
Merge pull request #1587 from bash0C7/fix_padrino_cache_example

Fix padrino-cache example comment
ensure that captured blocks in erb and slim templates return nil, fixes #1582
Merge pull request #1588 from minad/1582

ensure that captured blocks in erb and slim templates return nil, fixes #1582
Add .navbar .navbar-nav>.active.

Let the <li class="navbar-module active"> work.
Avoid improper checking, fixes #1584
Quick fix for the destroyer of sub application
Fix tests meaningless
Fix rr deprecation warning when using it together with rspec

This commit fixes the following error:

    DEPRECATION: RSpec::Core::Configuration#backtrace_clean_patterns is
    deprecated. Use RSpec::Core::Configuration#backtrace_exclusion_patterns
    instead.

...that appears when using rspec + rr. Since a while there's no need of
using the `conf.with_mock :rr` in Rspec conf. See more info [here][1].

[1]: https://github.com/rr/rr/pull/37#issuecomment-22833629
Drop the test code that requires webrat, fixes #1569
introduce Logger#exception method
cleanup application.rb, use new logger method
Merge pull request #1590 from padrino/fix-cucumber-component

Drop the test code that requires webrat, fixes #1569
Merge pull request #1591 from padrino/fix-destroyer

Avoid improper checking, fixes #1584
drop uuid, use SecureRandom.hex for random test names
fixes dependency error with macaddr and systemu
test logger.exception, fix backtrace
cleanup gemfile, dont test other gems
Merge pull request #1589 from Red54/patch-1

Add .navbar .navbar-nav>.active.
load config.ru with padrino server, fixes #1260
add an example of database.yml usage for datamapper, closes #899