[refactor] Components now return desired width/height directly, rather than
the minimum of desired width/height and offered width/height. Table now allocates
the minimum of desired/offered height appropriately.

This results in simpler component layout code, and lays the groundwork for simplifying the
requestedSpace interface from 4 fields to 2
[refactor] Reimplement`Component._isFixedWidth` (& height) using flags not trickery

Close #484
[refactor] Components now return desired width/height directly, rather than
the minimum of desired width/height and offered width/height. Table now allocates
the minimum of desired/offered height appropriately.

This results in simpler component layout code, and lays the groundwork for simplifying the
requestedSpace interface from 4 fields to 2
[refactor] Reimplement`Component._isFixedWidth` (& height) using flags not trickery

Close #484
Merge branch 'better-requested-spcae' of github.com:palantir/plottable into better-requested-spcae

Conflicts:
	plottable.js
Address Brian's feedback
Merge branch 'master' into better-requested-spcae

Conflicts:
	plottable.js
Merge branch 'master' into brs WITH merge conflicts

Conflicts:
	plottable.d.ts
	plottable.js
	src/components/legend.ts
Fix merge conflicts with legend
Fix unit test failure
Merge pull request #737 from palantir/better-requested-spcae

Better requested space
Merge branch 'master' into api

Conflicts:
	plottable.d.ts
	plottable.js