Finished implementation of builddata API

Finished implementation of builddata API

Updated the code and tests to handle this format of build target:
    <buildtarget name="atom">
      <buildconf>
        <location href="3bd64bd5fa862d99dbc363ccb1557d137b5685bc3bfe9a86bcbf50767da5e2e8-build.conf"/>
        <checksum type="sh256">3bd64bd5fa862d99dbc363ccb1557d137b5685bc3bfe9a86bcbf50767da5e2e8</checksum>
      </buildconf>
      <repo arch="i586" type="binary">repos/atom/i586/packages</repo>
      <repo arch="i586" type="binary">repos/atom/i586/debug</repo>
      <repo arch="x86_64" type="binary">repos/atom/x86_64/packages</repo>
      <repo arch="x86_64" type="binary">repos/atom/x86_64/debug</repo>
      <repo type="source">repos/atom/sources</repo>
    </buildtarget>

Change-Id: Ie300bff66699eb402af4b0ca7eaddc37a238c136