resolves #436 move style to instance variable

- convenience methods to check/retrieve role and reftext attributes
update zurb foundation to 4.2.2, adjust styles accordingly
Merge pull request #444 from mojavelinux/foundation-4.2.2-update

update zurb foundation to 4.2.2, adjust styles accordingly
Merge pull request #443 from mojavelinux/style-instance-variable

resolves #436 move style to instance variable
add captioned_title method to AbstractBlock
resolves #447 add html-pipeline as source-highlighter option

- also optimize listing & literal template as pure Ruby
Merge pull request #448 from mojavelinux/html-pipeline-highligher

resolves #447 add html-pipeline as source-highlighter option
optimize admonition template
Merge pull request #449 from mojavelinux/optimize-templates

optimize admonition template
resolves #451 upgrade font awesome to 3.2.0

- include test that font awesome link is included in HTML head
use captioned_title convenience method in backend

- also inline the title_div helper method
Merge pull request #452 from mojavelinux/font-awesome-3.2.0

resolves #451 upgrade font awesome to 3.2.0
resolves #438 add basic template cache
use custom cache instead of Tilt::Cache; cache scan result
Merge pull request #446 from mojavelinux/template-cache

resolves #438 add basic template cache
cleanup template cache handling, improve tests
fix test failures in renderer test on Ruby 1.8
fix test assertion
really fix failing test
resolves #457 honor showtitle attribute as alternate to notitle!