habanero v0.2.0

• user-agent strings now passed in every http request to Crossref, including a X-USER-AGENT header in case the User-Agent string is lost (#33)
• added a disclaimer to docs about what is actually searched when searching the Crossref API - that is, only what is returned in the API, so no full text or abstracts are searched (#32)
• improved http error parsing - now passes on the hopefully meaningful error messages from the Crossref API (#31)
• more tests added (#30)
• habanero now supports cursor for deep paging. note that cursor only works with requests to the /works route (#18)