BUG: fix #47.
BUG: fix old appinst handling.
Merge branch 'handle_old_appinst'

Fixes #87.
ENH: handle crash in a more user-friendly manner.
MAINT: remove unused launch code.
MAINT: remove unused modules.
MAINT: remove obsolete patch_egg functionality.
MAINT: remove bsdiff4 dev requirement.

It is not needed anymore since we've removed enstaller.zdiff module.
ENH: fix race conditions when checking time-related metadata.

We now ignore time-related metadata in eggcollect.
MAINT: remove obsolete TODO.
MAINT: update gitignore file.
Merge branch 'remove_obsolete_code'
ENH: properly handle egg-info handling for all cases.

We now distinguish between 3 cases:

    - for a non Enthought-built egg, we copy the content of EGG-INFO
      into $site-packages/$package.egg-info
    - for an Enthought-built egg built with egg_info_as_dir=False passed
      to workbench.EggCreator (the default), we copy the EGG-INFO
      content into the correct location inside site-packages, with a
      blacklist to ignore Enthought-specific bits.
    - for an Enthought-built egg built with egg_info_as_dir=True passed
      to workbench.EggCreator, we move the egg-info content into the
      correct location, and don't copy anything from EGG-INFO.
REF: remove unused is_custom_egg in get-dst and write_arcname.
BUG: Fix update when new egg matches one in lower prefix.

In case of multiple prefixes, an update would not be performed
in primary prefix if a lower prefix has the updated version,
despite the primary prefix having an older version of the egg
installed.
Merge pull request #138 from pankajp/fix-chained-overridden-update

BUG: Fix update when new egg matches one in lower prefix.

LGTM, merging.
Fix: Mock keyring for TestWriteConfig.test_simple too.

Allows all tests to pass in the Jenkins enstaller build job
BUG: ensure to remove the written egg-info files.
BUG: don't blacklist EGG-INFO/blacklist in custom eggs.

This is actually a standard feature of upstream egg format.
DOC: mention better egg installation in the Changelog.