Merge branch 'release/0.7.10'
Add optional logger to log every request

Just the possibility to set a logger for the Linode instance, either through initialize or the accessor. If it is given, then use it to log every single request. Nothing changes if it is not given.
Add support for missing API methods
Merge pull request #21 from robbertkl/master

Looks good.  Tests are :green_apple:
add a spec for passing in a logger
use accessor since we have it
bring README.md up to date
Merge pull request #22 from rick/more-work-on-logger

Land #19 (with additional tidbits)
Revise Linode API Docs url
added disk.createfromimage and disk.imagize
added account.estimateinvoice and account.list
added image.list and image.delete
added avail.nodebalancers
stop gitignoring Gemfile.lock
update rake & rspec
update mocha requires
update should_not raise_error to resolve deprecations
whitespace :lipstick:
get suite passing again

mocha stub/expects behavior is a bit different now
update .rspec to use newed doc formatter

fixes last deprecation warning