Pkg2: slight error/info messaging tweak.
give a chance to set USE_BLAS64 in Make.usr
use system libopenblas via set USE_SYSTEM_OPENBLAS=1
use var name LIBOPENBLAS_PATH while using system libopenblas
correct blas info in function `versioninfo'
Merge branch 'master' of github.com:JuliaLang/julia
Simplify Pkg2.resolve
Merge pull request #3615 from JuliaLang/kf/pkg2

Simplify Pkg2.resolve
Merge branch 'master' of github.com:JuliaLang/julia
Revert "Simplify Pkg2.resolve"

This reverts commit eeb34f7c1878922c98a1b696b9bd7db146422f43.

This is deeply broken. Resolve simply doesn't work.
remove reference to 'extras' dir from README
Allow launching child processes with different ENV
Remove unused environ on Mac
Refactor and consolidate the performance tests

Run perf tests by running make in test/perf
Factor out timing code into test/perf/perfutil.jl
Micro benchmarks are now in test/perf/micro/
perf2 benchmarks are now in test/perf/kernel
shootout benchmarks now run (not all yet) as part of the perf tests (#660)
cat benchmarks now run as part of the perf tests
Merge pull request #3618 from JuliaLang/vs/perf

Put a performance testing framework in place
Fix readdlm test.
Use joinpath correctly in readdlm test.
Download data for shootout tests as necessary.
Run k_nucleotide, regex_dna, and revcomp
Replace WGET and WGET_DASH_O with JLDOWNLOAD.
Enable IRC notification for failed Travis builds