title: Error with pod spec lint
body: <p>I want to public a framework.</p>
  
  <p>I have created a pod spec in my framework directory, fill pod spec information, then type <code>pod spec lint</code></p>
  
  <p>But it gives me error:</p>
  
  <pre><code>-&gt; KPImageView (1.0.0)
      - ERROR | [iOS] unknown: Encountered an unknown error ([!] /usr/bin/git clone https://github.com/khuong291/KPImageView.git
  /var/folders/t5/rgq4j6cn7h79khx0xsftrjtw0000gp/T/d20161113-67362-1dxzrg4
  --template= --single-branch --depth 1 --branch 1.0.0
  
  Cloning into
  '/var/folders/t5/rgq4j6cn7h79khx0xsftrjtw0000gp/T/d20161113-67362-1dxzrg4'...
  warning: Could not find remote branch 1.0.0 to clone. fatal: Remote
  branch 1.0.0 not found in upstream origin ) during validation.
  
  Analyzed 1 podspec.
  
  [!] The spec did not pass validation, due to 1 error. [!] The
  validator for Swift projects uses Swift 3.0 by default, if you are
  using a different version of swift you can use a `.swift-version` file
  to set the version for your Pod. For example to use Swift 2.3, run:
  `echo "2.3" &gt; .swift-version`.
  </code></pre>
  
  <p>my podspec:</p>
  
  <pre><code>Pod::Spec.new do |s|
    s.name         = "KPImageView"
    s.version      = "0.0.3"
    s.summary      = "UIImageView with Ken Burns effect."
    s.homepage     = "https://github.com/khuong291/KPImageView"
    s.license      = { :type =&gt; 'MIT' }
    s.author       = { "khuong291" =&gt; "dkhuong291@gmail.com" }
    s.source       = { :git =&gt; "https://github.com/khuong291/KPImageView.git", :tag =&gt; s.version.to_s }
  
    s.platform     = :ios, '7.0'
    s.requires_arc = true
  
    s.source_files = 'KPImageView/KPImageView/*'
  end
  </code></pre>