Update README.md

Hi,
I've been learning this mock framework these days. When I read the README file I found two missing links for the word "here" in the "Remember" part :
1. link to more documentation and examples
2. link to RefCard 
so I did these micro-modifications. I hope this will be helpful for you. 

Kuangshi
Merge pull request #58 from yankuangshi/patch-1

Update README.md with better links and documentation
Fixed javadoc for AdditionalAnswers
Added casts to supress varargs warnings
Merge pull request #56 from marcingrzejszczak/javadocFix

Fixed wrong javadoc for AdditionalAnswers
Adds a simple comment on the spy javadoc to explain some limitations regarding annotations which is indeed a current limitation of CGLIB
Merge pull request #59 from marcingrzejszczak/fixVarArgs

Added casts to supress varargs warnings
Updated version
Started using Gradle 1.12 (we'll use 2.0 soon).
Added targetCompatibility to the build. It does not change anything, because it was already derived from source compat. However, it's more clear for build readers.
Bumped wrapper version in the build file for consistency.
Removed unused import.
Added encrypted bintray api key to the travis file.
Added encrypted GH_TOKEN and MOCKITO_BINTRAY_API_KEY to the travis file.
Made changes in build infrastructure to enable automatic publishing from Travis CI.
Added '-dev' postfix to the version until release process is done.
Added initial automatic publication to bintray. For now, even forks are published but we probably need to change that.
Started using jcenter instead of maven central
Tweaked the log message.
Started using Gradle 2.0.