Correct typos in comments (#134)

Author: alexandear

constraint.go

@@ -107,7 +107,7 @@ func (cs Constraints) Check(v *Version) bool {
 // to '>0.2' it is *NOT* treated as equal.
 //
 // Missing operator is treated as equal to '=', whitespaces
-// are ignored and constraints are sorted before comaparison.
+// are ignored and constraints are sorted before comparison.
 func (cs Constraints) Equals(c Constraints) bool {
 	if len(cs) != len(c) {
 		return false

version.go

@@ -174,7 +174,7 @@ func (v *Version) Compare(other *Version) int {
 		} else if lhs < rhs {
 			return -1
 		}
-		// Otherwis, rhs was > lhs, they're not equal
+		// Otherwise, rhs was > lhs, they're not equal
 		return 1
 	}