CRM-13492 d6 & d7 url functions are identical except for one missing param on d6, move d7 to DrupalBase, delete d6 & d7 versions

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* CRM-13492: buildAmount Hook functionality changed -- difficult to use / undocumented
  http://issues.civicrm.org/jira/browse/CRM-13492
CRM-13492 specify  = TRUE on navigation menu - this will cause urls to have &amp; not & in them
(Am currently unsure about the ones which have inconsistently stored a '?' in the civicrm_navigation menu - ie.
http://issues.civicrm.org/jira/browse/CRM-13942?focusedCommentId=54821&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-54821
as I cleaned them out of my DB)

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* CRM-13492: buildAmount Hook functionality changed -- difficult to use / undocumented
  http://issues.civicrm.org/jira/browse/CRM-13492
Merge pull request #2277 from eileenmcnaughton/CRM-13492

CRM-13942  navigation menu is not valid html