RFR: 430: /summary command does not support multi-line summaries [v3]

[Erik Helin]

> Hi all,
> 
> please review this patch that makes the `/summary` pull request command accept multi-line summaries. As described on
> the [Skara wiki](https://wiki.openjdk.java.net/display/SKARA/Pull+Request+Commands#PullRequestCommands-/summary) the
> `/summary` command should this, since the commit message format allow for this.  Testing:
> - [x] Added a new unit test
> - [x] `make test` passes on Linux x64
> 
> Thanks,
> Erik

Erik Helin has updated the pull request incrementally with one additional commit since the last revision:

  Updates based on reviewer feedback
  
  - Handle preceeding empty lines
  - Handle trailing empty lines
  - Show error when command is used for both single- and multi-line
    summaries

-------------

Changes:
  - all: https://git.openjdk.java.net/skara/pull/678/files
  - new: https://git.openjdk.java.net/skara/pull/678/files/6d612ddf..202a7d37

Webrevs:
 - full: https://webrevs.openjdk.java.net/skara/678/webrev.02
 - incr: https://webrevs.openjdk.java.net/skara/678/webrev.01-02

  Stats: 161 lines in 2 files changed: 148 ins; 1 del; 12 mod
  Patch: https://git.openjdk.java.net/skara/pull/678.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/678/head:pull/678

PR: https://git.openjdk.java.net/skara/pull/678