prepare_report.py: Make parsing more lax to handle output from older compiler versions

test/scripts/fixtures/solc_0.4.0_cli_output.txt

@@ -0,0 +1,8 @@
+contract.sol:1:1: Warning: Source file does not specify required compiler version! Consider adding "pragma solidity ^0.4.0;".
+contract C {}
+^
+Spanning multiple lines.
+
+======= C =======
+Binary:
+6060604052600c8060106000396000f360606040526008565b600256

test/scripts/fixtures/solc_0.4.8_cli_output.txt

@@ -0,0 +1,10 @@
+contract.sol:1:1: Warning: Source file does not specify required compiler version!Consider adding "pragma solidity ^0.4.8
+contract C {}
+^
+Spanning multiple lines.
+
+======= C =======
+Binary:
+6060604052346000575b60358060166000396000f30060606040525b60005600a165627a7a72305820ccf9337430b4c4f7d6ad41efb10a94411a2af6a9f173ef52daeadd31f4bf11890029
+Metadata:
+{"compiler":{"version":"0.4.8+commit.60cc1668.mod.Darwin.appleclang"},"language":"Solidity","output":{"abi":[],"devdoc":{"methods":{}},"userdoc":{"methods":{}}},"settings":{"compilationTarget":{"contract.sol":"C"},"libraries":{},"optimizer":{"enabled":false,"runs":200},"remappings":[]},"sources":{"contract.sol":{"keccak256":"0xbe86d3681a198587296ad6d4a834606197e1a8f8944922c501631b04e21eeba2","urls":["bzzr://af16957d3d86013309d64d3cc572d007b1d8b08a821f2ff366840deb54a78524"]}},"version":1}