Remove classifier, dtl and gossiperl

The first two are gone, the latter depends on a dependency
that's gone and the project hasn't been maintained for 3 years.

index/classifier.mk

@@ -1,7 +0,0 @@
-PACKAGES += classifier
-pkg_classifier_name = classifier
-pkg_classifier_description = An Erlang Bayesian Filter and Text Classifier
-pkg_classifier_homepage = https://github.com/inaka/classifier
-pkg_classifier_fetch = git
-pkg_classifier_repo = https://github.com/inaka/classifier
-pkg_classifier_commit = master

index/dtl.mk

@@ -1,7 +0,0 @@
-PACKAGES += dtl
-pkg_dtl_name = dtl
-pkg_dtl_description = Django Template Language: A full-featured port of the Django template engine to Erlang.
-pkg_dtl_homepage = https://github.com/oinksoft/dtl
-pkg_dtl_fetch = git
-pkg_dtl_repo = https://github.com/oinksoft/dtl
-pkg_dtl_commit = master

index/gossiperl.mk

@@ -1,7 +0,0 @@
-PACKAGES += gossiperl
-pkg_gossiperl_name = gossiperl
-pkg_gossiperl_description = Gossip middleware in Erlang
-pkg_gossiperl_homepage = http://gossiperl.com/
-pkg_gossiperl_fetch = git
-pkg_gossiperl_repo = https://github.com/gossiperl/gossiperl
-pkg_gossiperl_commit = master