Added per-recipient merge variables support.
Encode Requests with UTF-8 to support German Umlauts in requests 

if i send have e.g an Recipient like this:

new MandrillRecipient("Andreas Lüdeke", "mail@bla.de")

mandrill returns a HTTP Status 500 wit message "you must specify a key value". This happens due to the fact that the ü is not properly encoded within the StringEntity. By Specifying the correct Encoding it works properly
Merge pull request #10 from ahapxor/master

Adding merge_vars to MandrillMessage
Merge pull request #11 from aluedeke/patch-1

Encode Requests with UTF-8 to support German Umlauts in requests
.gitignore
Merge branch 'master' of https://github.com/cribbstechnologies/Java-Mandrill-Wrapper
Added new Mandrill response reject_reason
Fixed "UTF-8" mispelling