feat(combineLatest): accept array of observable as parameter

[kwonoj]

closes #594

Applies same mechanics of forkJoin to support array of observables, to close issue.

[benlesh]

LGTM

[benlesh]

I presume that this didn't affect perf in any meaningful way (similar to the forkJoin change)?

[kwonoj]

I presume that this didn't affect perf in any meaningful way (similar to the forkJoin change)?

: yes, forgot to attach number in general number differences are acceptable in bounds.

before

                                 RxJS 4.0.7 | RxJS 5.0.0-alpha.10 |          factor |      % improved
-------------------------------------------------------------------------------------------------------
combinelatest - immediate | 6,340 (±13.40%) |     57,265 (±9.28%) |           9.03x |         803.2%
            combinelatest |  6,035 (±9.18%) |    46,885 (±12.88%) |           7.77x |         676.9%

after

                                 RxJS 4.0.7 | RxJS 5.0.0-alpha.10 |          factor |      % improved
-------------------------------------------------------------------------------------------------------
combinelatest - immediate | 6,340 (±17.19%) |     55,761 (±9.41%) |           8.79x |          779.4%
            combinelatest | 8,274 (±11.69%) |     48,748 (±6.96%) |           5.89x |          489.2%

I'll check in changes myself around tonight - tomorrow.

[kwonoj]

Merged with 2edd92c.