phabricator related changes:

• don't lint either contrib or crypto: these are both externally written

	  directories

• add additional linters for spelling (check common typos like teh ->

	  the)

• chmod linter checks for executible bit on bad files
• merge-conflict checks for merge conflict tokens then may have been

	  resolved incorrectly

• filename checks for back characters in filenames
• json for json syntax correctness

• remove history.immutable: it is meaningless on subversion, and causes

	  workflow problems when trying to use git.  It it set to 'true' by
	  default with hg