Added a warning message when the Main-Class does not exist within the jar file.
Added a unit test for the Main-Class warning in write-jar
Fixed the testing string for the test-write-jar function
Merge pull request #1595 from stuartfehr/master

Add warning when Main-Class doesn't exist in output jar
Don't wrap `:signing` in a map in the docs.

Fixes #1594. [ci-skip]
Update clj-http from 0.6.5 to 0.9.2

Update clj-http to a more recent version that contains fixes that are
useful in leiningen plugins.
Merge pull request #1596 from hugoduncan/feature/update-clj-http-to-0.9.2

Update clj-http from 0.6.5 to 0.9.2