Removed bootstrap.less from bower main property

[choffmeister]

As state at https://github.com/bower/bower.json-spec#main bower's main
property should contain only the compiled versions.

[cvrebert]

See #13328.

[cvrebert]

Due to lack of progress on that spec (particularly with regard to main; see bower/bower#935), it has unfortunately in practice become no longer controlling, and a few differing emergent conventions for main are now duking it out. Very disappointing, but true.

Is the presence of bootstrap.less causing any concrete issue for you?

[choffmeister]

No, I have no conrete issues. Just thought it would increase compatibility with the spec. But when the spec is out of date, then this PR is pointless. Also I see the argument, that having to much files in the 'main' property is better than having to less, since the unnecessary files can be filtered out by the build tools...

[juriejan]

I would actually benefit from the entire less directory being included in main. The bootstrap.less file is an entry point, but cannot work in it's own.

I make use of wiredep project to scan the main property of my bower components for files that I need to link to or move around in order for my build to work. Right now everything else in this package works fine apart from less dependencies.

[cvrebert]

@juriejan main is for entry points only. Putting all the Less files in main would deviate too far from the bower spec and from actual practice observed in other projects. Proper tooling should be able to resolve bootstrap.less's imports.