Fix deb compression type.

Unbreaks fpm-cookery with the latest fpm.
Add changelog for 0.17.1.
Bump version to 0.17.1.

Changes:

* Unbreak deb package building.
Oups, fix tests.
Add support for 'npm'.
Unbreak omnibus packaging.

Fixes #64
Start default revision at 1.

It seems to be conventional for deb and rpm to start the revision at 1.

https://www.debian.org/doc/debian-policy/ch-controlfields.html#s-f-Version
https://fedoraproject.org/wiki/Packaging:NamingGuidelines?rd=Packaging/NamingGuidelines#Package_Versioning
Change handling of version, revision and vendor attributes.

After reading some more about versioning for deb and rpm, I belive that
this is more correct.

For debs `<version>+<vendor><revision>` becomes
`<version>-<revision>+<vendor>`.

For rpms `<version>.<vendor><revision>` becomes
`<version>-<revision>.<vendor>`.

This should address the issues seen in #42.
Do not set a default value for vendor.

Should address #42 and #63.
Merge pull request #65 from Jimdo/npm-recipe

Add support for 'npm'
Add changelog for 0.18.0.
Bump version to 0.18.0.

Changes:

* Do not set a default value for the vendor attribute.
  WARNING: This changes the default package names!
* Change package name computation regarding version, revision and vendor.
  WARNING: This changes the default package names!
* Start default revision at 1.
* Unbreak omnibus packaging. (#64)
* Add support for npm recipes. (bracki / #65)
Correctly set version, iteration and vendor on the FPM object.

Should address problems in #63 and should produce packages with better
metadata.
Add changelog for 0.19.0.
Bump version to 0.19.0.

Changes:

* Correctly set version, iteration and vendor on the FPM object.
  WARNING: This changes the default package names!
Include directory entries to %files section for .rpm.

:rpm_auto_add_directories? attribute for fpm manages .rpm to have
both directory and file entries in %files. For the current behavior,
the generated .rpm leaves some empty folders on filesystem when it
got removed by "rpm -e" or "yum remove".
Merge pull request #67 from unakatsuo/enable-auto-add-dir

RPM should have directory entries in %files section as default.
Fix test description.
Port tests from minispec to rspec.
Use let instead of a method definition.