Removed SPM from readme as it is dead (#1108)
Removed SPM from readme as it is dead (#1108)

SPM is no longer running as of the 15th March 2016, see http://spmjs.io/.
jnordberg/async,andalm/async,jnordberg/async,hargasinski/async,hargasinski/async,arigo-software/async,rlugojr/async,caolan/async,ecasilla/async,ezubarev/async,andalm/async,rlugojr/async,arigo-software/async,ecasilla/async,suguru03/async,steverobb/async,suguru03/async,caolan/async,ezubarev/async,steverobb/async