title: conan.io - header only package
body: <p>I'm trying to create a simple demo <strong>header only library</strong> called <em>foo</em> and require it another library called <em>bar</em>.</p>
  
  <p>The structure of <em>foo</em> is this:</p>
  
  <p><strong>foo/include/foo.hpp</strong> - just a test header file...</p>
  
  <p><strong>foo/conanfile.py</strong></p>
  
  <pre><code>from conans import ConanFile, CMake
  
  class FooConan(ConanFile):
      name = "foo"
      version = "0.0.1"
      exports = "*"
  </code></pre>
  
  <p>export it using:</p>
  
  <pre><code>conan export steazzalini/testing
  </code></pre>
  
  <p><strong>bar/conanfile.txt</strong></p>
  
  <pre><code>[requires]
  foo/0.0.1@steazzalini/testing
  
  [generators]
  cmake
  </code></pre>
  
  <p><em>conan install</em> fails saying:</p>
  
  <pre><code>ERROR: Can't find a 'foo/0.0.1@steazzalini/testing' package for the specified options and settings
  
  - Try to build from sources with "--build foo" parameter
  - If it fails, you could try to contact the package author , report your configuration and try to collaborate to support it.
  
  Package configuration:
  - Settings:
  - Options:
  </code></pre>
  
  <p>Thanks in advance for the help!</p>