Bug 1027215 - Generic Python code for parsing reftest manifests; r=roc

The immediate goal of this patch is to give the build system and testing
tools the knowledge to identify reftest files and directories. Parsing
extra metadata out of reftest manifests is currently a non-requirement,
but may be supported some day.

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extra : rebase_source : 279680af28c9175f5babe458a57203e8b19ab724
extra : histedit_source : c0e463ea02f87a376ef48e2b25136e5f6be4e61a
Bug 1027215 - Rewrite print-manifest-dirs.py to use new manifest parser; r=roc

Now that we've established a slightly better Python reftest manifest
parser, switch the existing manifest parsing code in
print-manifest-dirs.py to use it.

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extra : rebase_source : 9559eb5aa47d08b9854a27ed012f2a795abc67f7
extra : histedit_source : 7a9a8942f9310c079a5ea4321a7f4f2ad17008d1
Bug 1027215 - Add reftest manifests to build config; r=mshal

reftest and crashtest manifests can now be added to the build
configuration via REFTEST_MANIFESTS and CRASHTEST_MANIFESTS,
respectively.

The master manifest files have been added to layout/moz.build.

This patch enables the deprecation of master reftest manifests but stops
short of doing it. In the future, we could declare reftest and crashtest
manifests in their nearest moz.build file and generate the master
manifest (consisting of a bunch of "include" directives) as part of
config.status.

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extra : rebase_source : 3503f787b14b24c38daf577a710e67b583476858
extra : histedit_source : 21e55b3d28ee83afb47f3f779251a13c2a90db5f