Merge pull request #889 from JonRowe/formatter_spec_valid_xml

Tweak formatter test html to pass `xmllint`
ruby-prof 0.13 (in Gemfile-custom.sample)
Merge pull request #905 from JonRowe/186_support

1.8.6 Support
describe behaviour of how shared examples behave in contexts
remove shared examples from world
move to talking to shared examples directly rather than on world
shared examples should be declared on the group they're used on, as they are now context specific
refactor specs so that shared_examples are declared in context
use correct spacing
rewrite feature
refactor to use a register (phase 1)
segregate main from example groups
collection of shared examples
describe deprecation behaviour for shared examples
refactor
parenthesis and spacing
explain behaviour of parent contexts with new behaviour
restore clearing shared examples on reset
update change log