Ensure slf4j api version 1.5.6 is present

[Trello 278](https://trello.com/c/9qisbLW5)

Apache otlu (OAuth lib used by orcid and rest webapp) brings in 1.6.1, but rest of DSpace 1.7 expects 1.5.6. Previously xmlui and dryad-rest-webapp didn't specify a version.

According to [slf4j docs](http://www.slf4j.org/codes.html#version_mismatch), all versions of slf4j-api are compatible, so it doesn't matter which one we use, but we have to use the same version api and binding

> Mixing mixing different versions of slf4j-api.jar and SLF4J binding can cause problems. For example, if you are using slf4j-api-1.7.7.jar, then you should also use slf4j-simple-1.7.7.jar, using slf4j-simple-1.5.5.jar will not work.

> NOTE From the client's perspective all versions of slf4j-api are compatible. Client code compiled with slf4j-api-N.jar will run perfectly fine with slf4j-api-M.jar for any N and M. You only need to ensure that the version of your binding matches that of the slf4j-api.jar. You do not have to worry about the version of slf4j-api.jar used by a given dependency in your project. You can always use any version of slf4j-api.jar, and as long as the version of slf4j-api.jar and its binding match, you should be fine.
Correct typo
Correct typo
removed emails from PLOS journals per J. Linn
Fix two more cases where contexts may not be completed
Merge pull request #781 from dleehr/fix-rest-contexts

Urgent fix for REST Webapp
Merge pull request #776 from dleehr/fix-slf4j-version

Ensure slf4j api version 1.5.6 is present
Merge pull request #779 from jamie-dryad/patch-42

removed emails from PLOS journals per J. Linn