[16.01] Drop unused peek method

[16.07] history contents api - remove the default flag override

since it is wrong and ignores the access permissions

[16.10] Fix test fixtures dependency.

It should have never been in the pinned requirements and has disappeared from PyPI.

[16.07] Fix galaxy.util.in_directory()...

Easy to see on Mac OS X since /tmp isn't really /tmp for instance:

```
% touch /tmp/moo
% python
>>> import galaxy.util
>>> galaxy.util.in_directory("/tmp/moo", "/tmp/moo")
False
```

... and this is why the Travis tests are failing under Mac OS X. Broken with 93a8bfc7.

[16.07] Fix regressions in library API

Introduced in commit 93a8bfc7

ftp schemes in the data_source tool.

ftp schemes in the data_source tool.

[16.07] Additional hardening for older releases

[16.10] Various bits of hardening from #4604

Similar to commit 2586df45 .

For all tox environments used in .travis.yml except the ones allowed to
fail.

[16.07] Various bits of hardening from #4604