add paging support in sms & set base url in common
update URL's and add Next() support in shortcodes
refactor and document accounts/

now passes golint
refactor & document common
realized it was silly to have a package for Account
make conference golint compliant

- changed the Muted attribute in ParticipantUpdate to a regular boolean
  because Twilio interprets no value as False which is the default
  boolean value.
make notifications golint compliant
Merge branch 'master' into list_paging
making numbers golint compliant
go vet compliance for whole repo!
make applications golint oompliant
make recording golint compliant
make transcription golint complieant
make usage golint compliant
make voice golint compliant
make TwiML golint compliant
fix spelling errors
Merge branch 'master' into list-paging

Conflicts:
	.travis.yml
expanding README
fix comment errors