Remove deprecated methods from Revision, SkinTemplate, and WikiPage

No uses found in core of Gerrit extensions.

- Revision::revText() (deprecated in 1.17)
- SkinTemplate::jstext() (deprecated in 1.21)
- WikiPage::quickEdit() (deprecated in 1.18)
- WikiPage::useParserCache() (deprecated in 1.18)
- WikiPage::viewUpdates() (deprecated in 1.18)

Change-Id: I9eee23ea3ce381b6b8373da899287bcaea4cead4
Merge "Remove deprecated methods from Revision, SkinTemplate, and WikiPage"