Add libexiv2 (#2593)

* Add libexiv2

* remove core dependencies

packages/libexiv2.rb

+require 'package'
+
+class Libexiv2 < Package
+  description 'Exiv2 is a Cross-platform C++ library and a command line utility to manage image metadata.'
+  homepage 'http://exiv2.org/'
+  version '0.26'
+  source_url 'http://www.exiv2.org/builds/exiv2-0.26-trunk.tar.gz'
+  source_sha256 'c75e3c4a0811bf700d92c82319373b7a825a2331c12b8b37d41eb58e4f18eafb'
+
+  def self.build
+    system "./configure --prefix=#{CREW_PREFIX} --libdir=#{CREW_LIB_PREFIX}"
+    system "make"
+  end
+
+  def self.check
+    system "make check"
+  end
+
+  def self.install
+    system "make", "DESTDIR=#{CREW_DEST_DIR}", "install"
+  end
+end