Minor README updates.
Minor README updates.

* Use more modern sounding compilers in 'Multiple Builds' section.
* Fix typos.

giorgiobornia/libmesh,hrittich/libmesh,BalticPinguin/libmesh,vikramvgarg/libmesh,jwpeterson/libmesh,svallaghe/libmesh,vikramvgarg/libmesh,dschwen/libmesh,balborian/libmesh,svallaghe/libmesh,dschwen/libmesh,vikramvgarg/libmesh,BalticPinguin/libmesh,vikramvgarg/libmesh,capitalaslash/libmesh,dschwen/libmesh,jwpeterson/libmesh,svallaghe/libmesh,roystgnr/libmesh,roystgnr/libmesh,pbauman/libmesh,90jrong/libmesh,roystgnr/libmesh,balborian/libmesh,svallaghe/libmesh,hrittich/libmesh,vikramvgarg/libmesh,capitalaslash/libmesh,90jrong/libmesh,svallaghe/libmesh,dschwen/libmesh,hrittich/libmesh,pbauman/libmesh,jwpeterson/libmesh,balborian/libmesh,BalticPinguin/libmesh,giorgiobornia/libmesh,pbauman/libmesh,balborian/libmesh,libMesh/libmesh,capitalaslash/libmesh,capitalaslash/libmesh,jwpeterson/libmesh,pbauman/libmesh,roystgnr/libmesh,capitalaslash/libmesh,jwpeterson/libmesh,giorgiobornia/libmesh,svallaghe/libmesh,libMesh/libmesh,libMesh/libmesh,balborian/libmesh,BalticPinguin/libmesh,balborian/libmesh,giorgiobornia/libmesh,roystgnr/libmesh,libMesh/libmesh,roystgnr/libmesh,pbauman/libmesh,capitalaslash/libmesh,pbauman/libmesh,90jrong/libmesh,dschwen/libmesh,hrittich/libmesh,jwpeterson/libmesh,90jrong/libmesh,BalticPinguin/libmesh,giorgiobornia/libmesh,giorgiobornia/libmesh,roystgnr/libmesh,pbauman/libmesh,svallaghe/libmesh,pbauman/libmesh,capitalaslash/libmesh,vikramvgarg/libmesh,BalticPinguin/libmesh,vikramvgarg/libmesh,giorgiobornia/libmesh,dschwen/libmesh,jwpeterson/libmesh,giorgiobornia/libmesh,BalticPinguin/libmesh,balborian/libmesh,libMesh/libmesh,pbauman/libmesh,90jrong/libmesh,roystgnr/libmesh,hrittich/libmesh,balborian/libmesh,svallaghe/libmesh,dschwen/libmesh,balborian/libmesh,svallaghe/libmesh,BalticPinguin/libmesh,giorgiobornia/libmesh,90jrong/libmesh,libMesh/libmesh,balborian/libmesh,90jrong/libmesh,libMesh/libmesh,vikramvgarg/libmesh,hrittich/libmesh,capitalaslash/libmesh,dschwen/libmesh,hrittich/libmesh,jwpeterson/libmesh,90jrong/libmesh,libMesh/libmesh,vikramvgarg/libmesh,90jrong/libmesh,hrittich/libmesh,hrittich/libmesh