homeTimeline is limited at most 15/user, so use userTimeline instead.
run integrated test only in GHCVAR=7.8.2
quit support GHC 7.2.2 and below, now only support GHC 7.4.1 and higher.

Now, upstream packages, for instances the http-client package,
depends base 4.5 and higher, so they support only GHC 7.4.1 and higher.
Reduce package dependencies