This change is prompted by npm-based builds, which tends to open
many files due to the 'microlibrary' approach that many javascript
projects take. In particular, horizon's npm-based builds were
running into this limit- while the tests were executing well, the
file open limit was exceeded during report generation.
This patch ups the soft limit from 1024 to 4096, and the hard limit
from 4096 to 8192 on all debian systems.
Change-Id: I8fc4a23eb34da88f7076a4c1ef2ec4c975dc450e