delete index file before writing to it (if change)

Otherwise, the file is writen in place and changes the hardlinked
ones too in older trees, therefore introduces inconsistencies in
older snapshotted trees.
Updated Translations
New translation-codes for the i18n-directory. Related to issue #9. Removed translations: ast,eo,eu,fa,ka,oc because there are no offical languages in ISO-3166-1 alpha-2.
Updating method get_variable for issue #17

Added a check for the method get_variable, because the fixed issue #17 (proxy support) need this. This check is needed because the variables 'proxy_user' and 'proxy_password' are optional.
Updating last commit, merged issue #17 and issue #10

A better idea to remove the little bug in issue #17. I have merged issue #17 and issue #10 for overview. The idea for the solution for issue #17 is from carmenates09.
Update postmirror.sh (description and example).
Fix typos in CHANGELOG.
Remove trailing spaces from .perltidyrc file.
Use warnings instead of passing -w in the shebang.
Add all tarballs to .gitignore.
Makefile: Do not overwrite existing mirror.list (fixes #18).
Release 0.5.0
fix find-translation-files bug

the lastest downloaded Release and Index files located in skel directory
but not the mirror directory.
Merge pull request #15 from dr4Ke/mirror_to_hardlinked_directory

Fix skel (indexes) updates in a hardlinked mirror
Run perltidy.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	apt-mirror
Added proxy support

Original change comes from GitHub-User <<carmenates09>>/<<apt-mirror>>@<<01833f2adf4a14ed14ef32ac0d85790826947119>>
Added default variables for 'proxy_user' and 'proxy_password' because this variables can be empty
Merge pull request #28 from selaselah/master

fix find-translation-files bug
Merge pull request #31 from EifX/master

Added Proxy support
Also mirror xz compressed files (fixes #25).
Set default use_proxy and http_proxy variables.