Bump duct/core version to 0.8.0

[kwrooijen]

Problem

Currently when generating a new Duct app and bumping the version to 0.8.0 I get this error:

user=> (dev)
Syntax error (FileNotFoundException) compiling at (repl.clj:1:1).
Could not locate hawk/core__init.class, hawk/core.clj or hawk/core.cljc on classpath.

This is because hawk was introduced in this PR:
duct-framework/core#24

Correct solution?

Quoted from this source: https://github.com/technomancy/leiningen/blob/master/doc/PROFILES.md#default-profiles

The :provided profile is used to specify dependencies that should be available
during jar creation, but not propagated to other code that depends on your
project. These are dependencies that the project assumes will be provided by
whatever environment the jar is used in, but are needed during the development
of the project. This is often used for frameworks like Hadoop that provide their
own copies of certain libraries.

I'm not sure if this means that the end user needs to supply this dependency, but that's what I understand from this quote.

Related Pull request:

#95

[weavejester]

Thanks for the commit, could you change the commit message to:

Update duct/core dependency to 0.8.0

This will be better for searching the logs, as it's more consistent with other commit messages.